Compression Results

[EyExR]

Rich conditions is a big enemy on fresh rings, especially.

M50 injectors with a chip is fine. People put them in because they think it will make the car run better, but working on these things every day for a living, the spark plugs tell me otherwise. Every car that comes in with larger injectors (yes, even 17.5) have spark plugs covered in soot.

Good to know. thanks

[ForcedFirebird]

Rich conditions is a big enemy on fresh rings, especially.

M50 injectors with a chip is fine. People put them in because they think it will make the car run better, but working on these things every day for a living, the spark plugs tell me otherwise. Every car that comes in with larger injectors (yes, even 17.5) have spark plugs covered in soot.

[EyExR]

I wouldn't doubt the larger injectors did it. Larger injectors without a matching chip does nothing for anyone.

It's SSSquid chipped for my car with M50 injectors. Although I now have a spare ECU in there at the moment for testing purposes. The M50 injectors are 17.5# so not much of a difference really... But I'm going to swap back to the M20 injectors just to test.

What did the leakdown numbers say? I don't recall seeing that anywhere.

Its weird that you're getting coolant in the airbox. Similar to what happened when my first motor took a dump at Summit Point Main. It regurgitated a bunch of coolant out the intake ... cylinder 3 blew up into bits. I don't know what happened with that motor but it had a cooling issue... maybe headgasket failure or a bad head. Can't comment on that with certainty.

Adam, remember the knock we heard? Could that be detonation??

Secondly... could detonation be causing the RICH mixture? (I'm not very knowledgeable here I admit).

The wet air filter is a mystery. I'll crack that box open again and see what's up now with a fresh one in there.

My gut feeling is that I'm losing compression from bore wash. My car has been getting the 1222 code for quite some time. Ignorant me never knew that could polish my cylinder walls. But now I know and the rich condition is now enemy #1

post #5

Yes. Cylinder #4 was dropping by about 30%. All the others looked good. Listened for air passing and it was real loud coming out of my dip stick tube.

I'm now thinking it could possibly be a bad purge valve. So I'll cap that at the intake and see. I've read that a bad purge valve can cause a car to run rich. I don't see how but I'll test it.

I also did not mention that I'm using an E34 O2 sensor because I have long tube headers installed. I hope that it's compatible as everywhere I've read says it is.

[digger]

What did the leakdown numbers say? I don't recall seeing that anywhere.

Its weird that you're getting coolant in the airbox. Similar to what happened when my first motor took a dump at Summit Point Main. It regurgitated a bunch of coolant out the intake ... cylinder 3 blew up into bits. I don't know what happened with that motor but it had a cooling issue... maybe headgasket failure or a bad head. Can't comment on that with certainty.

Adam, remember the knock we heard? Could that be detonation??

Secondly... could detonation be causing the RICH mixture? (I'm not very knowledgeable here I admit).

post #5

[dude8383]

What did the leakdown numbers say? I don't recall seeing that anywhere.

Its weird that you're getting coolant in the airbox. Similar to what happened when my first motor took a dump at Summit Point Main. It regurgitated a bunch of coolant out the intake ... cylinder 3 blew up into bits. I don't know what happened with that motor but it had a cooling issue... maybe headgasket failure or a bad head. Can't comment on that with certainty.

Adam, remember the knock we heard? Could that be detonation??

Secondly... could detonation be causing the RICH mixture? (I'm not very knowledgeable here I admit).

[ForcedFirebird]

I wouldn't doubt the larger injectors did it. Larger injectors without a matching chip does nothing for anyone.

[EyExR]

I forgot to mention I have M50 injectors. I don't see a problem with that but I'll put back my M20 injectors to see. And I'll check spray patterns on both for the heck of it.

Vacuum is not pulling fuel at the FPR so the diaphragm is good.

I'm going to do the valve adjustment next, check timing and open up my cap and rotor to make sure everything looks right and then finally check spark at every plug.

[EyExR]

Ok. Did some more tests today. I did another fuel pressure test and it was dead on perfect.

I also swapped in another ECU and put in some new plugs.

The car idles a little rough but that could be the ICV making up for the compression loss on my bad cylinder...

I made sure I had a 1444 code before I hit the road.

The car was actually running incredibly strong for all its issues. But then the Check Engine light came on. Went home and did the stomp test. Now I'm getting 1221. O2 sensor out of range or bad.

???

I had a 1222 on my last ECU now a 1221 on this one? What gives?

I made sure the plug was seated correctly and tried again. Same thing.

Strange

[EyExR]

Check the vacuum line on the fuel pressure regulator. Make sure the diaphragm isn't ripped and drawing fuel through it.

You can disconnect the charcoal feed from the bottom of the throttle body and cap the nipple there. That will eliminate that.

Also, pull up the fuel rail from the manifold, leaving the injectors attached along with the fuel lines and crank the car while paying attention to the spray pattern of the injectors. If one or all of them are dripping instead of spraying nice, it will cause rich conditions.

How would I check the vacuum line at the FPR? It has vacuum... How do I know if the diaphragm is torn? This is a new FPR that I put on for the latest rebuild, too. I really doubt it's shot.

For the injectors - am I to let them spray down into the cylinders? I'm assuming you can pry them up enough to look for the pattern but not get gas all over the place? It's pretty tight in there.

Could I have a bad catalytic converter?

anyone want to buy an essentially new iX with issues?? lol. seriously considering dumping this. I've been working on this car for years with no success.

[ForcedFirebird]

Check the vacuum line on the fuel pressure regulator. Make sure the diaphragm isn't ripped and drawing fuel through it.

You can disconnect the charcoal feed from the bottom of the throttle body and cap the nipple there. That will eliminate that.

Also, pull up the fuel rail from the manifold, leaving the injectors attached along with the fuel lines and crank the car while paying attention to the spray pattern of the injectors. If one or all of them are dripping instead of spraying nice, it will cause rich conditions.

[EyExR]

Okay. I had time to do some tests today to try and figure out why I'm running rich. I did the entire ECU pinout tests and some things came back a bit off. I'm not sure if they are the cause, however. Car has been sitting cold. Ambient temperature was 40 degrees F for all tests.

My reference sensor (CPS) (pins 47 and 48 ) read 833 ohms. The range is supposed to be 540 +/- 54 ohms.

The idle Air Stabilizer Valve (ICV) read 46.4 ohms. It's supposed to be 40 ohms.

Everything else seemed fine. The CTS had the correct resistance between pin 45 and ground. And my TPS was was functioning properly too..

I opened up the air filter box and I found my filter was wet from coolant. I'm not sure why...

So I replaced the air filter, cleaned and burned off the spark plugs, cleaned my ICV, cleaned the MAF, sprayed contact cleaner on every sensor and plug and added some dielectric grease to the C191 just in case.

I also pulled the fuel injectors and ran the fuel pump. No leaks...

I went for a 20 minute drive (car was surging a bit and revving high at idle...) and then my check engine light came on again. Got home and did the stomp test - 1222. Just like I had before. Pulled the plugs - and they already were fouled from fuel.

I guess my next course of action is to swap in another ECU, check timing, and do another valve adjustment. I've already done a fuel pressure test and it looked good. The return line is not crimped and I put a new FPR on...

Am I missing something? What else can I do?

I heard the purge valve kick on when doing these tests but could my charcoal canister be a culprit. What about my brake booster?

[EyExR]

Cool. Thanks!

Question regarding the CTS: When you guys unplug this while the car is idling do you get any change at all? I don't... It's a 1991 FWIW...

[ForcedFirebird]

Correct.

[EyExR]

Ok. Maybe I'll look into wideband. I don't want this to ever happen again.

So I'll have some time this weekend to start pecking through the list of possible problems. I plan on pulling my injectors and fuel rail and running my fuel pump with a switch. My question is when I do this, nothing at all should come out of the injectors. Correct?

[ForcedFirebird]

Widebend is the only real way to monitor fuel accurately.

Yes, if the walls are polished, 99% of the time is either poor break in, cylinder washing, or both.

Codes with these old ECU's really aren't of much help as they only will let you know once something has completely failed, or is unplugged.