Can't figure out why engine is running rich

[chrisesteschiro]

Ok, my brother bought a 525 with a m20b25 in it, the car will start right up and idle fine but whenever you hit the accelerator pedal it will get to about 2k rpms and them surge back and forth terribly, it will eventually rev up to 6k but it is very far from drivable. The exhaust smokes and smells of gas. We have new plugs (which are soaked in gas), cap, plugs, wires, all look good. Took off valve cover, no broken rockers or anything. We replaced the injectors, and fpr, still runs the same, hell it runs the same if you pull a plug wire off.......engine light says injector 1 or group one but injectors are new, also says fuel pump relay control, but we replaced and tested all the relays. We checked coolant temp sensor and it was reading the right amount of ohms, AFM getting right amount of volts.........I think that the AFM might be flat broke, or cat clogged up and exhaust pressure can't get out..........car has 240 K...........Please help your ideas are greatly appreciated.

Thanks,
Chris Estes

[delatlanta1281]

Ecu?

[TS87325IS]

did you check the tps on the bottom of the throttlebody?

[NC325iC]

i would say just to see if this fixes it reset the ecu

unhook the ground cable from battery for like half an hour or so

[ptownTSI]

new o2 sensor, check for vacuum leaks, crank sensor.

[chrisesteschiro]

There are 0 vacuum leaks, battery has been disconnected for a day, I don't have the bentley handy, how do I test the crank sensor and the TPS? I am also going to throw a new comp. in it the weekend....Thanks for your help.

[delatlanta1281]

What was the last thing done to it?
Are you positive there is no leak? Take CRC carb cleaner and spray it through the four holes that are between the runners on your intake manifold so you can get to its seals. What year is this car? What is the numerical code it is giving you?

[chrisesteschiro]

Its a 1989, we have taken the intake mani off twice and replaced any hoses that looked suspect, it was giving us I think its 1261? Anyhow it was fuel pump relay control, now it is giving us 1251 Which is injector 1 or group 1. ? (numbers I am recalling could be wrong but I'm sure these are what they equated to) I am 100% sure that relays are good and relay sockets are also. We bought the car running like this and we were sure it was a vacuum leak or injectors, but now we are stumped......

[delatlanta1281]

it may be the ecu

[delatlanta1281]

The injector and spark signals come from the ecu i believe....
Check the injector pulse with a power probe, low impedence to see if you are getting a pulse signal or a constant.... you should get a pulsing ground or a pulsing power, but not both or neither.
It can't be the cat though, it wouldnt foul plugs, or make a leaky injector. How's the compression on it btw?

[chrisesteschiro]

Thanks for the help, I'm working on it this afternoon, and will let you know how it goes........

[delatlanta1281]

What happened with this?
If you can get it to chamblee, my buddy can probably give you a hand for a nominal fee.

[bpittmane34]

Heey I'm the guy that owns the car. I finally had an opportunity today to check the compression and it was as follows starting with #1....90,60,90,120,90,60. BAD NEWS. I don't know if it jumped timing or what so I guess I may pull the front off and see if the marks line up and look for missing teeth and such as that...But I really think it's just time to find an M30 and a 5spd....

[bpittmane34]

I don't know if anyone will even read this, but I pulled the head off of it and found that the cylinder walls shine like chrome! The rings are worn slap the f@#k out! So it's time for an engine. And a turbo. A big turbo. Anybody got a 5spd pedal assembly and shifter assembly for an E34 lying around?