DIY_EFI Digest Sunday, 29 June 1997 Volume 02 : Number 219 In this issue: Re: fuel rail Re: Big overlap cams and EFI RE: Please post Re: Big overlap cams and EFI Re: fuel rail Re: fuel rail Hi, I'm new here :-) Re: Hi, I'm new here :-) Toyota MAFs See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Christopher G. Moog" Date: Sat, 28 Jun 1997 06:12:52 -0400 Subject: Re: fuel rail Jim Davies wrote: > > On Fri, 27 Jun 1997 jb24@xxx.com wrote: > > > Actually, the 2.5L Jeep engine is made by Chrysler, in the same plant > > as the 4.0L I6. It is a REALLY old design. > > > Well, first there was the AM 232 6cyl, then the 258, then they cut 2 > cylinders off it (which later became the 2.5L) then they added 2 > cylinders to the 2.5 to make the 4.0 I6...in a nutshell > > Jim Davies Originally International Harvester (232, 258). ------------------------------ From: Joe Boucher Date: Sat, 28 Jun 1997 07:14:49 -0500 Subject: Re: Big overlap cams and EFI At 06:55 PM 6/27/97 -0500, you wrote: >Joe Boucher > You can use the remote vacuum pumps [external] that came on many of the GM >cars of the 80s if you have a low vacuum. >Good Luck >Greg Abarr > That's not what I'm getting at. The ECM goes nuts and won't manage the fuel properly. Why? Joe Boucher 70 RS/SS Camaro 81 TBI Suburban Bedford, TX ------------------------------ From: Joe Boucher Date: Sat, 28 Jun 1997 07:50:25 -0500 Subject: RE: Please post At 01:22 PM 6/27/97 +0100, you wrote: > The LPG fuel systems usually retro-fitted to vehicles are >totally independent of the gasoline systems., ie the gasoline ECU has >nothing to do with the LPG fuel metering. >> ---------- >> From: boughton@xxx.net] on behalf >> of James Boughton[SMTP:boughton@xxx.net] >> Sent: 26 June 1997 23:52 >> To: 'diy_efi@xxx.edu' >> Subject: RE: Please post >> >> Michel, >> Here is my guess (and believe me I am guessing). On typical >> gasoline injection cars there is a function which decreases the >> pulsewidth for a short period of time on open to closed throttle >> transitions. This is to keep the engine operation near stoichiometric >> while the puddled fuel in the intake manifold gets sucked into the >> engine. With the LPG fuel there is no puddling and the decrease in >> pulsewidth is actually forcing the engine lean causing the bump your >> friend is feeling. As I am not familiar with the control system of >> the 730i or LPG fuel I am shooting in the dark, but there is my >> explanation :-) >> >> Here's another thought. If this system was a hack job, did they put in a O2 sensor adapter. Propane stociometric (SP?) is around 15.5. If the O2 sensor is sending back a standard signal and the computer thinks its using gasoline and tries to maintain 14.7 and it should be 15.5, maybe that's part of the problem. And that is a guess also. Joe Boucher 70 RS/SS Camaro 81 TBI Suburban Bedford, TX ------------------------------ From: Roger Heflin Date: Sat, 28 Jun 1997 08:40:10 -0500 Subject: Re: Big overlap cams and EFI Joe Boucher wrote: > > The guy at Turbo City that will burn custom prom chips for GM EFI told > me the maximum intake duration he can burn a chip for is 220 degrees. > > What is the problem? It 's centered around the vacuum signal, correct? > Is the MAP sensor incapable of keeping up with the rate of change or > magnitude of the signal? Does the vacuum get too low (air pressure too > high) versus the map in the prom? If you didn't care about emisions, > could you program the prom so the manifold pressure is ignored when the > throttle position is at idle and just squirts a certain amount of fuel > based on coolant temperature? With a MAP based fuel management system > is the fluctuation of the vacuum signal at low RPM's too wild versus the > sampling rate of the computer to determine the dwell of the injectors. > > In other words, I don't have a clue why this is. > > Thanks, > > Joe Boucher > '70 RS/SS Camaro '81 TBI Camaro > Bedford, TX There a couple of guys on the f-body list running cams above 220 degrees, I don't know exactly how far above, but they claim they don't run too bad. I have heard one of them idle and it does die sometimes if you are doing the wrong thing (coming out of the water box off of the gas). I don't really know how many degrees they are running, just that is significanlty more radical than the LT4-HOT (218/228) cam. They have put the cams in both a 93 Z28 (prom/maf) and the 94+ (map). They claim that they idle better in the 94+. Roger 93 Z28 (wondering if I can put up with their cam) rah@xxx.net - -- ------------------------------ From: Jim Davies Date: Sat, 28 Jun 1997 08:55:10 -0700 (PDT) Subject: Re: fuel rail On Sat, 28 Jun 1997, Christopher G. Moog wrote: > Jim Davies wrote: > > > > On Fri, 27 Jun 1997 jb24@xxx.com wrote: > > Well, first there was the AM 232 6cyl, then the 258, then they cut 2 > > Originally International Harvester (232, 258). > They used the 232, IIRC, but the engines are original AMC designs. Jim Davies ------------------------------ From: Sketch Date: Sat, 28 Jun 1997 17:21:41 -0400 (EDT) Subject: Re: fuel rail > When I had my '85 Jeep Cherokee (Pre Chrsyler takeover) I had a choice > between a GM 2.8 V6 and a GM 2.5L I4. I'm pretty sure all of the early > 2.5's were GM engines. One can probably use the fuel rail from a later > fuel-injected Chevrolet Celebrity or any application with the fuel injected > 2.5. (Fiero?) All Fiero 2.5's were TBI, as were all of all other models, at least through 88 or so. So you won't be finding a fuel rail off of one, unless they switched over later to a PFI setup. C'ya Fiero! http://erau.db.erau.edu/~byrnee Sketch '86 Fiero SE V6 - 4 speed ------------------------------ From: Ed Date: Sun, 29 Jun 1997 00:01:21 -0700 Subject: Hi, I'm new here :-) Hello, I'm a new subscriber to this list. I discovered the web page and emailed Johnny asking for more info on a reasonably-priced wideband a/f meter. He prompted me to join the list. So here I am. I've dabbled a bit in tuning aftermarket EFI, and worked in a shop that had a chassis dyno, so the the tweaking aspect is something I've grasped. But when it comes to subjects like building a digital ignition system or any sort of thing like that, I'm boggled. So you'll probably find me posting a lot of questions, so please be patient with me. Hopefully I can contribute something too. :-) - -Ed ------------------------------ From: Sandy Date: Sat, 28 Jun 1997 22:53:03 -0700 Subject: Re: Hi, I'm new here :-) Welcome new blood! Sanduy At 12:01 AM 6/29/97 -0700, you wrote: >Hello, > I'm a new subscriber to this list. I discovered the web page and >emailed Johnny asking for more info on a reasonably-priced wideband a/f >meter. He prompted me to join the list. So here I am. > I've dabbled a bit in tuning aftermarket EFI, and worked in a shop >that had a chassis dyno, so the the tweaking aspect is something I've >grasped. But when it comes to subjects like building a digital ignition >system or any sort of thing like that, I'm boggled. > So you'll probably find me posting a lot of questions, so please be >patient with me. Hopefully I can contribute something too. :-) > >-Ed > > ------------------------------ From: Ed Date: Sun, 29 Jun 1997 02:46:38 -0700 Subject: Toyota MAFs Does anyone know of a larger mass airflow sensor available for 93-on Toyotas, namely the Supra? What most Supra owners do is replace the MAF with a device from HKS called a VPC (vein pressure converter) when upgrading to a larger turbo, etc.,hanging the fuel system to a speed-density system. It's basically a MAP sensor with a black box that sends the proper signal to the ECU. The box contains several adjustment knobs for fuel pulse, gain, and idle mixture. Only problem with this device is the constant need to readjust the VPC when there is a large change in air temperature and humidity. If there is no available upgraded MAFs, how hard would it be to use MAF from a Mustang? A friend of mine has the chance of getting a larger aftermarket Mustang MAF that has the proper interface required to work with his 95 Eagle Talon TSi, would the work required to do the same for a Toyota run a lot more than $1000 (usuall price for a VPC)? - -Ed ------------------------------ End of DIY_EFI Digest V2 #219 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".