tbi problems

[MUD MAN]

Ok. So I got mine running a lot better by putting a different fuel pump on it but it still dies when I put it in gear????

 

[doctordick]

Had a thought today (hate when that happens) Is your IAC working? That could account for the weird idle and cause a lean condition at wider throttle opening. Foot off the gas, engine warm, does the RPM come back up when you put it in gear or start to drag the clutch ? If you have access to a scantool, you can operate the IAC with the engine off. If not, you should be able to watch it operate with the engine running by removing the air cleaner and spacer ring and looking straight down into the opening above the end of the IAC. Try it with the engine cold, the pintel should extend and then slowly retract as the engine warms up. That's an advantage and a disadvantage of the earlier computers, they can only tell if a part is shorted or open, not if it's just not working mechanically. That lack of diagnostic power is also what lets us get away with murder without reprogramming compared to the newer engine systems. Hope this helps, lemme know.

Try this. Idle should be 650 rpm in neutral with the engine warm. When you pull it in gear, it may pull down a little but come right back to 650. Around 900 rpm cold. If you don't have access to a scantool, there really isn't any way to test the IAC ir ECM function. It would be cheaper to have a shop check it than buying a new one or ECM.

 

[doctordick]

Alexander City, al how about you

I'm over 100 miles from you. What type of meter did you use? Did you read 5v or 1/2volt? (hard to see on my screen) Did you try to drive it with the MAP disconnected? It should have run pretty normally if the MAP sensor was the problem. If you were only reading 1/2 volt on the grey wire and across the grey and purple wires, that's way too low. Since you've subbed the ECM, the problem would about have to be in the harness or a ground issue. Are you using an OEM harness or aftermarket? The OEM harness has two black wires with white tracers that end together in an eyelet terminal. This is the ground for many of the functions (not all) And it needs a really good zero resistance connection.

 

[RBaker]

I used a fluke meter to check the voltage it read .5 volts across the purple and grey wires

 

[RBaker]

I am using a painless harness and I have checked the grounds in the harness they are grounded on a intake bolt. Were else do I need to ground. Should I have a ground from the motor to the frame.

 

[doctordick]

Definately needs ground from engine block to frame. Try moving the harness ground wire to an alternator mounting bolt. Where is the battery grounded?

 

[doctordick]

Sorry, man. I guess I wasn't clear. Use the peak hold function on your meter and check grey to purple with the sensor disconnected. Should read around 5v. Reconnect the sensor and measure green wire to ground, should be around 1v. If your meter doesn't have peak hold, you can use AC scale, voltages will be roughly 7/10 of spec. Peak hold is better if you have it.

 

[MUD MAN]

Trying to get my hands on a scantool now

 

[musselman]

Are ya'll running a stock tbi cam???

 

[doctordick]

Are ya'll running a stock tbi cam???

That's a good question that I didn't ask, but more cam duration would cause vacuum to be low and it seems his MAP sensor is reading too high (lower voltage) Low vacuum = higher voltage, high vacuum = low voltage

 

[RBaker]

Can't remeber the duration on the cam but when I ordered the rebuild kit from national auto I talked to the salesman and he said it hazd the same specs as stock. I know for sure it is computer compatible.

 

[musselman]

Check the pick-up in the distributor.

 

[RBaker]

How can I check it without replacing the dizzy. I am going to the buggy bash if any of you guys are going to be there to look at this little jeep I would appreciate it.

 

[musselman]

pull the dizzy spin it make sure it spins free any kind of hang up replace also have seen rust cause problems

 

[RBaker]

Finally think I may have gotten somewhere with the motor after this weekend at the buggy bash. I fouled the spark pluggs late saturday and when I got home I checked the regulator in the throttle body and realized it was shot. Replaced the regulator and also grounded the body to the motor. After all this I also realized a couple of my plug wires were burnt from the headers. So I replaced them and know she runs better. :****:

 

[doctordick]

Very cool, glad you got 'er runnin' better. I fought a similar problem on my Willys, and after I got it figured out, I put a fuel pressure gauge on it. Makes catching a fuel issue real easy. Hey Mudman, you do any good with your junk?

 

[MUD MAN]

Well I took my junk for a little test run yesterday and it does good trail cruising and does great on steep hill climbs but the damn thing still dies when I put it in gear or change from drive to reverse?

 

[doctordick]

Only three things I can think of: IAC not working, low fuel pressure, or bad/wrong injectors. You haven't messed with the mechanical idle adjustment have you? If not, DFWI (don't fawk with it).

 

[MUD MAN]

Fuel pressure is good and scantool said IAC was good so maybe I need some new injectors then. Any suggestions on them?

 

[doctordick]

I've never figured out a good way to identify the injectors, there is supposed to be a paint dot, different colors for 4.3, 5.0 and 5.7. but i guess the paint isn't gasoline resistant. Maybe you could borrow some, they're about $80 apiece, too much to spend on guesswork. I'm working on a tester, but I need to have a couple of parts made, so it will be a while before it's working.