TBI conversion running rich TBI gurus wanted

1983Bronco

1983Bronco

Well-Known Member
Joined
Apr 10, 2005
Location
On your mom in Winston Salem NC
I've got an 89 YJ I have been working on that has a 350 chevy with a TBI setup. The setup was installed before I bought the jeep. It starts up great, but runs rich as hell, if you putt putt around on the trail for 20 minutes or so it starts to foul plugs, the computer is out of a 87 g-20 chevy van and the motor is 30 over with a small cam, doesnt lope bad or anything, where should I start, I have heard a lower degree thermostat can cause problems, not real familiar with TBI so any help would be great, thanks in advance:beer:
 
what fuel pump you running ? Need to put a fuel pressure guage on it..

If I had to guess, you using a E2000 pump that everyone recommends and its over powering the regulator and thus suppling more fuel than the computer is tuned for.
You can either:
1) regulate the pressure down to what it can deal with, 10-12 (or even 15 isn't gonna kill it)
2) retune the chip to tell it what pressure its dealing with. This will adjust the injector on/open time during the squirt...

what year is the engine ?

Cat or t-state shouldn't affect much unless its below 180 than it depends on the ECM/Chip as to how much it does..

No mention of a O2 sensor ?

Have you got an ALDL port ? (have a laptop ?)
 
homemade harness or aftermarket?

X2 on the o2 sensor
 
O2?
MAP?

What is left what was deleted.
Like the 2 above me, I can probably think if 8-10 different things that would cause the exact problem described.
 
I am at work now, I will check when I get home, I am pretty sure it has an o2 sensor IIRC, it does still have the port for diagnostic, also beleive the harness came off the van, but I will check. The pump is a cylindrical style, not sure of the manufacturer, I will test the pressure.
 
yager said:
what fuel pump you running ? Need to put a fuel pressure guage on it..

If I had to guess, you using a E2000 pump that everyone recommends and its over powering the regulator and thus suppling more fuel than the computer is tuned for.
You can either:
1) regulate the pressure down to what it can deal with, 10-12 (or even 15 isn't gonna kill it)
2) retune the chip to tell it what pressure its dealing with. This will adjust the injector on/open time during the squirt...

what year is the engine ?

Cat or t-state shouldn't affect much unless its below 180 than it depends on the ECM/Chip as to how much it does..

No mention of a O2 sensor ?

Have you got an ALDL port ? (have a laptop ?)
Click to expand...

I have run a datsun 280z pump on mine for years no issues
 
yager said:
what fuel pump you running ? Need to put a fuel pressure guage on it..

If I had to guess, you using a E2000 pump that everyone recommends and its over powering the regulator and thus suppling more fuel than the computer is tuned for.
You can either:
1) regulate the pressure down to what it can deal with, 10-12 (or even 15 isn't gonna kill it)
2) retune the chip to tell it what pressure its dealing with. This will adjust the injector on/open time during the squirt...

what year is the engine ?

Cat or t-state shouldn't affect much unless its below 180 than it depends on the ECM/Chip as to how much it does..

No mention of a O2 sensor ?

Have you got an ALDL port ? (have a laptop ?)
Click to expand...




So I assume if its pumping too much pressure it will cause it too run rich, can I get a decent regulator from the local parts store? Also the engine is from a 70's truck, sorry thats all the info I have on it
 
:) Ahhh 70s motor.... Was gonna ask what year the motor was... I had to tune out this problem on my '72 307 engine and I still have some of this when its cold or WOT..

Basically the carb cam shaft has a lumpy idle, vacuum signal. sounds nice but this confuses the ECM. Even at idle its seeing the vacuum pulses and things its under load and dumps fuel. I had to tune this out in a few tables to get my 307 (305 TBI starting point) to even stay running when cold. Get your laptop on it and if you can keep it running see what how much vacuum your seeing at idle. If you don't want to get into tunings, just swap in a TBI cam shaft and this should get the ECM in the ball park and i will run just fine..

The higher pressure pump (e2000) can put out 60+ psi and a worn out regulator (even TBI) will have a hard time holding it back all the time. As far as datsun pump working, it just all depends on the specs. Many will work just fine. some times a new TPI pumps are just to much where a 100k mile junk yard unit will work np.. Thats what the guage is for.. But my $ is on the carb cam shaft...
 
pressure is dead nutz 15 psi, the map sensor seems to be working, when you unplug the vac line the motor dies, the air idle control and throttle plate sensor look new, I cleaned both of them, motor runs 10x more rich on startup, once it warms up its not as bad, one thing worth mentioning is it seems to run aroun 180-185 degrees, so could the lower thermostat be partially to blame, Yager I'm beginning to think you are right about the carb cam, looks like somebody replaced alot of the sensors before me. It has a test port plug, but no check engine light, so I cannot test it by counting the check engine light flashes to get a code.
 
Is there someone who makes a chip that can fool the computer into thinkinking its getting more vaccum. I assume the map sensor is sensing the vac. Can I fool it some how? Thanks
 
also has an edelbrock intake, not sure if that makes a difference, motor is out of a 1970 chevy truck, but cam was changed according to PO, but he does not know the specs
 
label on computer looks like this


serv. no. 1227747 AKMH

86AKMH K190722168

----------------------------------------------
16083051

86AKMHK190722168
 
google 'winaldl' its a free software program that will allow you to monitor your engine. You will need to buy a cable to attach the aldl port to either a serial or usb port on a computer. You will be able to view whats going on with the sensors. You will not be able to tune/reprogram it without some chip work.

go to thirdgen.org site and look in the TBI and DIY-PROM sections, read for 2 weeks. The site has loads of info on wiring sensors etc..

A chip with a proper tune (for your engine) won't 'fool' the ECM (computer) it will tell it exactly whats going on. The tables in the chip will contain correct fuel values to use vs ones that provide to much fuel.

I'd get your check engine light hooked up and/or use a laptop to see whats going on with it. That way you can make an informed decision about what to look at next vs just changing sensors and stuff hoping it works.
 
One word of caution here! IF you get a third party involved in helping you with your TBI issues, and IF he suggests that he stop by on his way to the western part of the state to look at it, and IF he does stop by..........From past experience I can tell you it will be right at dinner time, no he won't have eaten, and "well....if you don't mind, sure I'll stay for dinner". Now he knows your pattern and the next time he stops by, and he WILL need to stop by again, guess when he's going to show up? This is all hypothetical BTW :)
 
CYJKrawler said:
One word of caution here! IF you get a third party involved in helping you with your TBI issues, and IF he suggests that he stop by on his way to the western part of the state to look at it, and IF he does stop by..........From past experience I can tell you it will be right at dinner time, no he won't have eaten, and "well....if you don't mind, sure I'll stay for dinner". Now he knows your pattern and the next time he stops by, and he WILL need to stop by again, guess when he's going to show up? This is all hypothetical BTW :)
Click to expand...

But didn't Mik....I mean he get it solved?
:flipoff2:
 
Actually solved itself right before our eyes as we watched the brand new NAPA fuel pump spec'd at 9-15 psi drop to 4 psi as it went bad. New fuel pump fixed most of the problems along with some of Mi..er...the guys expertise and sure, engine runs great now, it's just that now I have to fix Chiles Relleno everytime my TBI has an issue :)
 
Yager, I'll be honest I am not much of a computer techno guy, matter of fact I gurantee that I would mess it up, would you be interested in taking a look at it for some cash. Thanks again for all the info.

Brad
 
found a guy that says he can llok at the jeep while its running then create a custom chip for $250, is that a decent deal. Thanks
 
There is alot of good info on installation and trouble shooting the tbi systems at binder bulletin. I'm currently running tbi from a 4.3 on a jeep 4.2 and it works great! But you will pull your hair out until you understand how they work. Alot of guys on this site are willing to help from trouble shooting to setting up the computers.
 
Previous owner here, The harness is a Affordable Fuel Injection piece. Camshaft is designed for TBI not carbed vehicles. It is a low end torque cam only. It has a chip from Affordable Fuel Injection in it already. TBI had a new regulator put in it. E2000 pump @ 15 psi constant. New MAP sensor, IAC motor, TPS, Coolant temp sensor etc... I personally think the chip from AFI is where I went wrong. The guy wasn't to specific when asking questions about what the chip was for. Probably needs something different burned for it. Cam card was in one of the manuals I gave with the Jeep. Hope this helps, miss the hell out of that thing.
 
damn dude, thank for the info, I wish I knew it had 15psi before I spent an hour making an adapter for my pressure gauge from lowes!:lol:, I think the guy in the hardware section was getting ready to call security because I kept opening up the packages, he was gettin a little ancy with the walkie talkie. Thanks again 02dmax, that info will really help out when I take it to get a chip burned, local guy in randleman said he can hook up the jeep and burn a custom chip, hope he's right!
 
02dmax said:
Previous owner here, The harness is a Affordable Fuel Injection piece. Camshaft is designed for TBI not carbed vehicles. It is a low end torque cam only. It has a chip from Affordable Fuel Injection in it already. TBI had a new regulator put in it. E2000 pump @ 15 psi constant. New MAP sensor, IAC motor, TPS, Coolant temp sensor etc... I personally think the chip from AFI is where I went wrong. The guy wasn't to specific when asking questions about what the chip was for. Probably needs something different burned for it. Cam card was in one of the manuals I gave with the Jeep. Hope this helps, miss the hell out of that thing.
Click to expand...


Did you ever try running it with the stock chip? If so how did it run? thanks
 
It ran like shit. Very rich. Only minimally better with the chip from AFI. Glad I could help
 
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