Compression Results

[EyExR]

Just because the TPS clicks doesn't mean anything, you need to read dead short at opposing pins in idle or WOT mode with a multimeter. Should test the sensors at the ECU connector as that is what the ECU actually sees after the harness.

If you have a later model with the round connector under the manifold, this connector often corrodes and can throw off CTS readings, make injectors misfire, not fir or all three.

o2 sensor being bad can cause the ECU to run rich, so can exhaust leaks pre-o2 sensor.

The ICV "shouldn't" cause it to run rich, but may - usually it will stick and cause low or high idle.

Thanks! I'll test those things too.

The C191 connector under the manifold looks good. No corrosion at all and well-seated. Although I never rule anything out.

This is my 3rd O2 sensor and I believe this running rich issue may have been an ongoing problem even before my initial rebuild. Over the years the plugs have looked very similar to what I posted. I had always assumed it was mostly oil but I'm thinking it may have been fuel the entire time. Killing my first engine, accelerating the failure of the initial rebuild and now this latest rebuild. Would polished cylinder walls point DIRECTLY to the problem?

Is there any other way of checking the fuel/air mixture besides just looking at plugs and checking codes? It would be nice to get results instantly while I go through the list of possible culprits...

[ForcedFirebird]

Just because the TPS clicks doesn't mean anything, you need to read dead short at opposing pins in idle or WOT mode with a multimeter. Should test the sensors at the ECU connector as that is what the ECU actually sees after the harness.

If you have a later model with the round connector under the manifold, this connector often corrodes and can throw off CTS readings, make injectors misfire, not fir or all three.

o2 sensor being bad can cause the ECU to run rich, so can exhaust leaks pre-o2 sensor.

The ICV "shouldn't" cause it to run rich, but may - usually it will stick and cause low or high idle.

[EyExR]

So I visited Dennis at OMG Motorsports in Farmingdale. I've been wanting to get over there for a while now as I see they're doing some really cool things for our 'community'. VERY cool guy and he knows his stuff. He did a smoke test and it revealed some small vac leaks at the cam plugs (not a big deal really...). So I will get that squared away when I rebuild.

He also tested resistance at the CTS and it read good. My AFM is new and I had cleaned my ICV not too long ago. But it is original so still somewhat suspect. The throttle position sensor also 'clicks' at the correct spot. That seems good.

He suggested that I check for continuity at the ECU end of the CTS. I'll do that next. Perhaps I have a bad harness?

My cap, rotor, coil, and plug wires are all new and I do get good spark at all plugs. No doubt they are fouled up from excessive fuel, however.

My hope is to get this car running with the proper fuel/air mixture and then tear her down. Yeah. I'd bet good money I'll find a couple of polished cylinder walls and probably a ton of carbon buildup on the piston tops...

[jeffnhiscars]

Since the o2 is before the cat I don't see how the cat can effect your readings but it is def possible that the sensor has a connection issue or that your ECU is not up to par in correcting the mixture.

[ForcedFirebird]

Some of you may have followed my saga on E30Tech. http://www.e30tech.com/forum/showthread.php?t=117652

I remember now :(

You had issues with the machine shop and ended up rebuilding on your own.

Please don't give up, keep that IX alive!

[digger]

surely over fueling (except in cause of faulty injector) causing bore wash will affect all cylinders and result in lower numbers across the board.

[EyExR]

Smoke test revealed some vac leaks at the front and rear cam plugs. But I'm still getting an O2 code popping up. So I'm still not sure why I'm running rich.... I'm leaning toward a bad cat as this is my second new O2 sensor since I started having the problem. Could also be a bad harness??

Well, on to tearing her down for a third time. I may sell the car once I have it back up to snuff and working properly. I'm starting to get tired of the iX I'm sorry to stay. Especially how plush my E34 touring felt on the road today in comparison...

[EyExR]

Yeah. Torco.

I'm bringing it in to get checked out and smoke tested on Tuesday.

Part of me wants to dump the project entirely and get a good working used engine. It would probably be the most sane thing I've done it a while but I really wanted this stroker project to turn out for the best. I've got to think about it some more and weigh the pros and cons.

Some of you may have followed my saga on E30Tech. http://www.e30tech.com/forum/showthread.php?t=117652

As she sits:

[Bullhead]

Well with the low psi in #4 and the car using a lot of oil, you have a washed out cylinder wall. Did you run a zinc based break in oil for the first 500 miles? Some say it isn't needed but I have always ran one to help the cam break in and it also helps the cylinder walls seal up.

[EyExR]

Have you ran a wide band on the car? I agree with John super rich according to the plugs. Is the car using oil? Does your oil have fuel in it?

No wide band. Yes the car is burning a ton of oil...

[Bullhead]

Have you ran a wide band on the car? I agree with John super rich according to the plugs. Is the car using oil? Does your oil have fuel in it?

[EyExR]

I've also read it could be my CTS or O2 sensor. But everything is brand new and I'm not sure how to solve this if the car is already running poorly due to compression loss.

I'm thinking of bringing my car over to the guys at OMG to diagnose....

[e30 gangsta]

Yes. That too. I don't know why.. What would cause that?

Also - why would one of my rings fail after just a few thousand miles on a fresh rebuild? So strange.

I guess my next step would be to pull the head and see if I discover anything before removing the block.

tune, ecu, fpr, leaky injector check all those first before rebuilding the motor.

[ForcedFirebird]

My guess is running rich washed the walls and polished the cylinder bore.

[EyExR]

Yes. That too. I don't know why.. What would cause that?

Also - why would one of my rings fail after just a few thousand miles on a fresh rebuild? So strange.

I guess my next step would be to pull the head and see if I discover anything before removing the block.