DIY_EFI Digest Friday, 13 December 1996 Volume 01 : Number 380 In this issue: Re: Weird problem Re: Weird problem Re: Fwd: eddy current brake Re: Weird problem Re: Fwd: eddy current brake Re: MAF Sensors Placement Re: Weird problem Re: Fwd: eddy current brake Re: MAF Sensors Placement re: Re: Fwd: eddy current brake Re: Weird problem, dumb question Re: Weird problem re: Re: Fwd: eddy current brake Re: Weird problem RE: MAF Sensors Placement Re: Fwd: eddy current brake RE: MAF Sensors Placement Re: oil pumps (not efi) Nissan 300ZX efi fault See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Gregory Chan" Date: Thu, 12 Dec 1996 09:18:55 EDT Subject: Re: Weird problem > > > I have been on this list now for quite a while now and I > > have learnt much about fuel injections systems, however, I have a > > problem which I am at a loss to solve. The car is a Toyota Corolla > > GTS with a 4AG motor. I have 10.5:1 pistons, 288 cams and a tweaked > > stock EFI system. > > What do you mean by tweaked. Sounds like whoever recalibrated your > ECU also added a speed governor. Does the ECU monitor which gear you > are in or vehicle speed? If it monitors vehicle speed, try disconnecting > the sensor just to see what happens! > Mazda, The term tweaked refers to adjustment of the AFM pot and disabling the EGR valve. The ECU is stock and all the work on the car was done by myself hence my joining this list to expand my knowledege of EFI systems. Thanks, gchan@xxx.ca ------------------------------ From: Chris Howard Date: Fri, 13 Dec 1996 01:27:40 +1100 Subject: Re: Weird problem At 13:27 12/11/96 EDT, you wrote: >Hi all, > I have been on this list now for quite a while now and I >have learnt much about fuel injections systems, however, I have a >problem which I am at a loss to solve. The car is a Toyota Corolla >GTS with a 4AG motor. I have 10.5:1 pistons, 288 cams and a tweaked >stock EFI system. The motor redlines the gears up to 4th, however, >5th does not go past 6,000 rpm and I am losing quite a lot of top >speed here as the redline is at 7,500 rpm. I have done an indicated >speed of 210 km/h with the present wheel/tire combination and a stock >engine @xxx. > Has anyone here experienced something like this before and can >offer some suggestions? Any suggestions are welcome. > Have you dynoed the car? Is the power peak above 6000? Maybe there is a drop in the power curve at 6000 which makes you top out there in 5th. Try going down a hill, it might make it past 6000 and then go all the way. Good luck, Chris Howard Computer Science University of New South Wales email: s2184002@xxx.au Web: http://www.usyd.edu.au/~choward - Aussie Touring Car Action ------------------------------ From: Mark Eidson Date: Thu, 12 Dec 1996 08:42:32 -0700 Subject: Re: Fwd: eddy current brake It's my understanding that the dynamic range, 20:1, is difficult for a simple PLL. I think the confuser would have to adjust the feedback based on the current RPM range to keep it locked. me At 04:37 PM 12/11/96 -0600, you wrote: >>Hi there, >> >>think the Eddy.effect is exlained enough, so lets go back where the idea came >>from (can't remember who it was, but what it was): >>reducing/removing backlash of the ignition rotor! > >Help me understand ..... (I've listened to related discussions re >ignition control for a while) > >I hear the 4 pointed star crank pickup isn't good enough to use >a PLL to develop nth degree resolution. > >Same for the distributor pickup. > >So, seems everyone wants to use either the flywheel teeth or a gear >attached to the cam (maybe even the cam gear??). Is that right? > >I know n-nothing -- at least not practically. Seems to me the crank >pickup with PLL would work. Any variation due to speed of the tooth >approaching the pickup giving faster rise time ergo changing reference >could be compensated for either in an analog circuit or in a confuser >using either a lookup table or (probably) a simple trig function. >I don't think the crank's gonna have much backlash :-) > >As far as backlash, why wouldn't an averaging function take care of >that? After all, how fast can an engine change speed? and the delta-speed >seems to me to be the most egregious factor (pun) in successfully >implementing some kind of smoothing circuit (maybe even an f-v convertor ??) > >Now, there's an idea I absolutely haven't explored .... Do an f-v conversion >and filter it ??? would that work? > > >Tom Cloud > > > *************************************************************************** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and Home: (602)831-6079 * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *************************************************************************** ------------------------------ From: "Gregory Chan" Date: Thu, 12 Dec 1996 10:57:19 EDT Subject: Re: Weird problem , you wrote: > >Hi all, > > I have been on this list now for quite a while now and I > >have learnt much about fuel injections systems, however, I have a > >problem which I am at a loss to solve. The car is a Toyota Corolla > >GTS with a 4AG motor. I have 10.5:1 pistons, 288 cams and a tweaked > >stock EFI system. The motor redlines the gears up to 4th, however, > >5th does not go past 6,000 rpm and I am losing quite a lot of top > >speed here as the redline is at 7,500 rpm. I have done an indicated > >speed of 210 km/h with the present wheel/tire combination and a stock > >engine @xxx. > > Has anyone here experienced something like this before and can > >offer some suggestions? Any suggestions are welcome. > > > > Have you dynoed the car? Is the power peak above 6000? Maybe there is a > drop in the power curve at 6000 which makes you top out there in 5th. Try > going down a hill, it might make it past 6000 and then go all the way. > Chris, I haven't dynoed the car as I am not a serious racer and the car is used for highway racing, hence my need for top speed. I just can't get past 6,000 rpm even down a hill. gchan@xxx.ca ------------------------------ From: Mark Eidson Date: Thu, 12 Dec 1996 08:51:09 -0700 Subject: Re: Fwd: eddy current brake I believe the new Corvette engine uses both cam and crank position sensors. Does anyone know how many trigger points are on the crank? It seems that the big boys have decided that a crank sensor is necessary, the question is how are they determining position for ignition timing? me At 07:36 PM 12/11/96 -0500, you wrote: >tom cloud wrote: >> >> >Hi there, >> > >> >think the Eddy.effect is exlained enough, so lets go back where the idea came >> >from (can't remember who it was, but what it was): >> >reducing/removing backlash of the ignition rotor! >> >> Help me understand ..... (I've listened to related discussions re >> ignition control for a while) >> >> I hear the 4 pointed star crank pickup isn't good enough to use >> a PLL to develop nth degree resolution. >> >> Same for the distributor pickup. >> >> So, seems everyone wants to use either the flywheel teeth or a gear >> attached to the cam (maybe even the cam gear??). Is that right? >> >> I know n-nothing -- at least not practically. Seems to me the crank >> pickup with PLL would work. Any variation due to speed of the tooth >> approaching the pickup giving faster rise time ergo changing reference >> could be compensated for either in an analog circuit or in a confuser >> using either a lookup table or (probably) a simple trig function. >> I don't think the crank's gonna have much backlash :-) >> >> As far as backlash, why wouldn't an averaging function take care of >> that? After all, how fast can an engine change speed? and the delta-speed >> seems to me to be the most egregious factor (pun) in successfully >> implementing some kind of smoothing circuit (maybe even an f-v convertor ??) >> >> Now, there's an idea I absolutely haven't explored .... Do an f-v conversion >> and filter it ??? would that work? >> >> Tom Cloud > > >The problem with all this is that it is an estimate. What we care >about, at least in the ignition system, is the exact location of the >piston when the plug is fired. The most accurate way to do it is by >monitoring the crank. I'm just gonna throw this out there (i.e. I'm not >sure about this): It seems to me the amount of error in a distributor >measurement is a function of engine speed and rate of acceleration. The >engine speed factor would probably not be a linear function, and the >rate of acceleration should affect the system because of additional >strain on the timing belt / chain. Right? >It's obvious picking up the signal off the distributor works, but I'd >almost always rather make a direct reading than to read a sensor and >then perform calculations (or look-up) to figure something out. > > *************************************************************************** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and Home: (602)831-6079 * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *************************************************************************** ------------------------------ From: Mark Eidson Date: Thu, 12 Dec 1996 09:01:22 -0700 Subject: Re: MAF Sensors Placement It seems that if you have capability and desire to play with you system that MAP is a good choice becasue it is simpler/cheaaper to implement physically. I have noticed the effect of acceleration and deceleration on mixture on my system but don't have the capability to compensate for it. me At 06:23 PM 12/11/96 -0800, you wrote: >Mark Eidson wrote: >> >> Todd, with the problems you have described does MAP work better for these >> applications? me > > >Mark, > Map does get rid of the back flow, turbulence, low speed resolution hot >wire type problems, but doesn't get rid of the intake manifold resonance >problem and certainly comes with its own share of problems. It needs >barometric, temperature and acceleration compensation, and does not >correct for engine changes over the long term. Small changes on the >engine also affect the map sensor system whereas the hot wire works fine >with camshaft, cylinder head, and exhaust changes improving the flow. > I've personally had quite a few bad experiences and currently go to MAP >on all our high performance systems and have been very happy with it. >If I were an OEM, I would probably think hard towards using MAF, but >they don't run 750hp through a 3.6l twin-turbo 911 either. > >Todd Knighton >Protomotive Engineering > > *************************************************************************** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and Home: (602)831-6079 * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *************************************************************************** ------------------------------ From: Todd Knighton Date: Thu, 12 Dec 1996 08:55:42 -0800 Subject: Re: Weird problem Gregory Chan wrote: > > > I have been on this list now for quite a while now and I > > >have learnt much about fuel injections systems, however, I have a > > >problem which I am at a loss to solve. The car is a Toyota Corolla > > >GTS with a 4AG motor. I have 10.5:1 pistons, 288 cams and a tweaked > > >stock EFI system. The motor redlines the gears up to 4th, however, > > >5th does not go past 6,000 rpm and I am losing quite a lot of top > > >speed here as the redline is at 7,500 rpm. I have done an indicated > > >speed of 210 km/h with the present wheel/tire combination and a stock > > >engine @xxx. > I haven't dynoed the car as I am not a serious racer and the > car is used for highway racing, hence my need for top speed. I > just can't get past 6,000 rpm even down a hill. Gregory, Will the thing ever go beyond 6,000, even with no load sitting in the parking lot? Is the power up to 6,000 rpm respectable or is it a slow fall off? Does your modified system have some built in rev limiter you don't know about? When the thing stops at 6,000 rpm's is the engine misfiring, smooth, backfiring, does the tach jump, do you notice black smoke out the tail pipe? Do you have an air fuel monitor on the engine, if so what's the fuel doing. Is your dwell set properly? or is it a function in the computer? Is your spark plug gap too large, coil too weak, rotor phasing off? We need more input to help you solve this one. Todd Knighton Protomotive Engineering ------------------------------ From: Markus Strobl Date: Thu, 12 Dec 1996 10:56:14 -0600 (CST) Subject: Re: Fwd: eddy current brake > I believe the new Corvette engine uses both cam and crank position sensors. > Does anyone know how many trigger points are on the crank? It seems that > the big boys have decided that a crank sensor is necessary, the question is > how are they determining position for ignition timing? me I have a '96 GM LT1 V8. It has the following sensors: Crank trigger: 4 positions. ONLY used for misfire detection. This was first introduced in 1996 with OBDII. Low res cam driven: 4 positions. Used for ignition timing High res cam driven: 180 positions. Used for ignition timing. The low & high res are really just one sensor and then there's a little box that makes it into a high res and a low res signal. The engine will run without the low res but it will crank longer before starting. A added bonus with the crank trigger is that the PCM can compare it's reading with the high-res cam signal and thus know how worn the timing chain is. Pretty neat. The wear factor (expresed in degrees) can be read with a scantool. - ------ Markus Strobl 1996 Z28 6-speed. Black/Grph. Various Mods Dallas, Texas http://www.allinfosys.com/fbody/markus.htm ------------------------------ From: Todd Knighton Date: Thu, 12 Dec 1996 09:04:36 -0800 Subject: Re: MAF Sensors Placement Mark Eidson wrote: > > It seems that if you have capability and desire to play with you system that > MAP is a good choice becasue it is simpler/cheaaper to implement physically. > I have noticed the effect of acceleration and deceleration on mixture on my > system but don't have the capability to compensate for it. me Mark, The easiest way is just like a carburetor. Reference throttle position movement and enrich, or enlean the mixture according to throttle position and velocity. Todd Knighton Protomotive Engineering ------------------------------ From: SRavet@xxx.com Date: Thu, 12 Dec 96 11:27:54 CST Subject: re: Re: Fwd: eddy current brake Markus Strobl Wrote: | I have a '96 GM LT1 V8. It has the following sensors: | | Crank trigger: 4 positions. ONLY used for misfire detection. This was first | introduced in 1996 with OBDII. Interesting. Any idea how this works? - --steve Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: Walters Chris Date: Thu, 12 Dec 96 10:45:00 MST Subject: Re: Weird problem, dumb question >Will the thing ever go beyond 6,000, even with no load sitting in the parking lot? >Is the power up to 6,000 rpm respectable or is it a slow fall off? >Does your modified system have some built in rev limiter you don't know about? >When the thing stops at 6,000 rpm's is the engine misfiring, smooth, backfiring, does the tach >jump, do you notice black smoke out the tail pipe? I've heard people refer to this as "loading up" the engine. What's really happening? Guess I've never revved my big old V8 high enough to experience it. Snake no cool Fords yet, one cool Dodge ------------------------------ From: "Gregory Chan" Date: Thu, 12 Dec 1996 13:18:16 EDT Subject: Re: Weird problem > > Will the thing ever go beyond 6,000, even with no load sitting in the > parking lot? It goes up to the 7500 rpm redline up to 4th gear. > Is the power up to 6,000 rpm respectable or is it a slow fall off? It pulls pretty strongly from 4500 rpm as compared to a stock motor. > Does your modified system have some built in rev limiter you don't know > about? The only thing that I did to the EFI was disabling the EGR valve and adjusting the AFM for more gas. > When the thing stops at 6,000 rpm's is the engine misfiring, smooth, > backfiring, does the tach jump, do you notice black smoke out the tail > pipe? It's smooth, doesn't backfire and I've only run it that hard twice. > Do you have an air fuel monitor on the engine, if so what's the fuel > doing. Nope. No AFMonitor. > Is your dwell set properly? or is it a function in the computer? > Is your spark plug gap too large, coil too weak, rotor phasing off? Dwell is OK. I reduced the spark plug gap the 2nd time. Coil? Rotor is new. > > We need more input to help you solve this one. > > Todd Knighton > Protomotive Engineering > ------------------------------ From: Markus Strobl Date: Thu, 12 Dec 1996 13:24:55 -0600 (CST) Subject: re: Re: Fwd: eddy current brake > Markus Strobl Wrote: > | I have a '96 GM LT1 V8. It has the following sensors: > | > | Crank trigger: 4 positions. ONLY used for misfire detection. This was > first > | introduced in 1996 with OBDII. > > Interesting. Any idea how this works? > > --steve They just look for uneven acceleration. That is, one pulse would alway come slightly delayd if that cylinder is dead. The misfire indications are put in a register in the PCM. Each cylinder has it's own register. If there are too many misfires in a given time, it set a code and flashes the service engine light. Markus ------------------------------ From: Todd Knighton Date: Thu, 12 Dec 1996 13:50:49 -0800 Subject: Re: Weird problem Greg, So what seems to be the relationship between 5th gear and the engine revving up. Almost sounds like a speed limiter to me. Just out of curiosity, what's your speed at 7500 in 4th versus 6000 in 5th, can you go faster in 4th than 5th? When in 4th gear does the thing have good power all the way to 7500, or does it significantly fall off? Any other changes, trans, tire, something else that may have affected it? Todd Knighton Protomotive Engineering ------------------------------ From: John Hess Date: Thu, 12 Dec 1996 08:49:13 -0600 Subject: RE: MAF Sensors Placement My first inclination would be at the inlet. This represents the actual air volume being let into the intake system at the actual temperature. The measurement (provided the MAF is able to measure this volume) should be most representative of the actual volume of air consumed by the engine. - ---------- From: Mark Eidson[SMTP:mark.eidson@xxx.com] Sent: Tuesday, December 10, 1996 2:25 PM To: diy_efi@xxx.edu Subject: MAF Sensors Placement In turbocharged or supercharged systems should the MAF sensor be placed at the inlet, between the impeller and intercooler or between the intercooler and intake manifold? me *********************************************************************** **** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *********************************************************************** **** ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Thu, 12 Dec 1996 16:51:00 -0600 Subject: Re: Fwd: eddy current brake >It's my understanding that the dynamic range, 20:1, is difficult for a >simple PLL. I think the confuser would have to adjust the feedback based on >the current RPM range to keep it locked. me > Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a 4-star crank sensor, you get a pulse every 45 degrees, since 2 revs = 360, right? Then, if you PLL'd the freq by 45, you'd have 1 degree pulses, by 90, .5 degree. Am I right? I think I understand the need for 'reasonable' accuracy with firing, but you've already got a hardware (crank) 45 degree reference. The PLL jitter shouldn't give but only a few tenths of a degree error, if that much. Capture shouldn't be a problem, as I don't see how you can rev or decelerate the engine fast enough to lose lock. Remember, I'm just positing here -- never actually tried this. Tom Cloud ------------------------------ From: John Hess Date: Thu, 12 Dec 1996 17:15:21 -0600 Subject: RE: MAF Sensors Placement Unfortunately, the MAP system requires EPROM recalibration for seemingly modest changes in the engine. The MAF system, while quite probably unable to produce the power the MAP system can (increased restriction of the MAF sensor), it adapts much easier to engine modifications. John - ---------- From: Mark Eidson[SMTP:mark.eidson@xxx.com] Sent: Thursday, December 12, 1996 10:01 AM To: diy_efi@xxx.edu Subject: Re: MAF Sensors Placement It seems that if you have capability and desire to play with you system that MAP is a good choice becasue it is simpler/cheaaper to implement physically. I have noticed the effect of acceleration and deceleration on mixture on my system but don't have the capability to compensate for it. me At 06:23 PM 12/11/96 -0800, you wrote: >Mark Eidson wrote: >> >> Todd, with the problems you have described does MAP work better for these >> applications? me > > >Mark, > Map does get rid of the back flow, turbulence, low speed resolution hot >wire type problems, but doesn't get rid of the intake manifold resonance >problem and certainly comes with its own share of problems. It needs >barometric, temperature and acceleration compensation, and does not >correct for engine changes over the long term. Small changes on the >engine also affect the map sensor system whereas the hot wire works fine >with camshaft, cylinder head, and exhaust changes improving the flow. > I've personally had quite a few bad experiences and currently go to MAP >on all our high performance systems and have been very happy with it. >If I were an OEM, I would probably think hard towards using MAF, but >they don't run 750hp through a 3.6l twin-turbo 911 either. > >Todd Knighton >Protomotive Engineering > > *********************************************************************** **** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and Home: (602)831-6079 * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *********************************************************************** **** ------------------------------ From: Darrell Norquay Date: Thu, 12 Dec 1996 20:46:58 -0700 Subject: Re: oil pumps (not efi) At 07:20 AM 12/11/96 -0600, Tom Cloud wrote: >The high volume pump does not increase pressure, so no more oil >flows through the engine than for a normal pump, unless there's >a loose fitting or such, right? A high volume pump will, in fact, increase oil pressure in most cases. I say in most cases since if bearing clearances are loose, it may not increase pressure over stock, but it will have higher pressure over a stock pump, which would be below normal in this case. This is a band-aid solution, however, if the engine has proper clearances, the high volume pump will not be necessary. > - same volume of oil will be pumped by stock and hi-vol pump (i.e. >hi-vol pump will just recirculate and 'froth' the oil). The only >time the hi-vol capability will be needed is when the engine is >very old or has an internal 'leak'. WRONG. Why the heck would it be called a high volume pump if it didn't pump more volume per revolution?!?!? If you carefully compare the stock pump with a high volume pump, you will note the body of the pump is longer, denoting longer gears in the pump, and thus more swept area of the rotors. More area x same RPM = higher volume. This will equate to higher average oil pressure, all else being equal. The only circumstance the oil pump recirculates is if the filter is allowed to clog up, at which point there is a bypass valve in the block which still allows oil to circulate, albeit unfiltered. > - you are advised to buy a hardened, stronger oil pump drive shaft >when you get a hi-vol pump ...... this implies to me that there's >more of a load on the shaft, hence on the cam gears, on the cam >'bearings',on the timing chain and gears. Why would you do that? The increased load is proportional to RPM. If you plan on redlining the engine at 8000 RPM, I would recommend the hardened shaft, if you don't plan on running above 5500 or 6000 RPM, don't bother. > - my 302 in my F150 with 107,918 (as of this morning) reads very >near the same oil pressure it did when it was new (on the "A" of >"NORMAL", heh-heh). It does this even when hot, down a quart and at >idle of 650 rpm (once again, as of this morn). All this means is that your engine is still in reasonable shape internally. A high volume pump doesn't last any longer than a stock pump under the same conditions. >Neither my mentor/guru nor my part$ guru could tell me why I should >use a high volume pump. Seems to me to really just be a waste of >_precious_ horsepower and a source of unnecessary wear on the cam >and related components. This is true. Having cleared up a few inconsistencies in your above comments, there are very few reasons to use a high volume pump. To quote David Vizard (How to Build Horsepower, S-A Design Books): "Most stock oil pumps supply sufficient oil flow for modified street engines." "In most engines, abnormally high oil pressure (above 45-50 PSI), increases pump drag, absorbs engine power, increases the chance of oil entering the combustion chambers, and does not provide improved bearing lubrication or extend component life." "Higher oil pressure will almost always do only one thing: rob horsepower, often as much as 10-15 HP when pressures of 100 PSI are used." BTW, don't even think of re-using the old pump. regards dn dnorquay@xxx.com ------------------------------ From: Ross Forgione Date: Fri, 13 Dec 1996 15:26:54 -0600 (CST) Subject: Nissan 300ZX efi fault Hi all, I work with a high flying sales person type dude, who is in his 30's and is suffering from the old mid life crisis problem. Soultion to problem, purchase a sporty type car. The car is a Nissan 300ZX model listed below. Anyway long story short, he bought second hand from a local car dealer after lots of warning from myself. Has spent lots of $$'s fixing the usual faults with cars, (hoses, leaking fuel seals etc ...) but there is one fault that even the local Nissan (real 100% factory appointed) cannot resolve. I have listed it below in the hope that somebody out there may be able to light a small candle showing the direction we should take in resolving the fault. Have pity on the guy, It real hard to look cool when the cars on tow as the pretty ladies go by. Any help at all will be greatly appreciated. The problem as follows: Make: Nissan 300ZX Turbo 1986 - Fuel Injected About 80% of the time the engine has a problem of surging then dying when at 1700-1900 RPM it refuses to cruise at this RPM level. The engine still accelerates and decelerates smoothly but will not run evenly whilst trying to keep at a constant speed. The problem can be fixed 100% successfully after driving a few KMs by putting the car into neutral and switching the ignition off for 2 or more seconds the restarting the engine. If I park the car and leave it for an hour or so the majority of the time I will need to start the engine drive for a few KMs the switch the engine off and on to get it to run smoothly again. If I start the engine then stop it immediately then start it again when I first get into the car it still will not cruise at 17-1900 RPM most of the time. Hot or Cold weather makes no discernable differance to the behavior of the car. It is a bit of nuisance having to switch the engine off every time I drive it. I have taken the car to a Nissan Service Centre but they are not sure what the problem is. They think it may be one of the computers being faulty but they are not sure which. I dont think much of having to pay $1500 to have both computers replaced when they are not certain which one it is or even if it is actually a computer fault. If you can find anyone that has had similar gremlims let me know. Thanks, Ross. ------------------------------ End of DIY_EFI Digest V1 #380 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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