M20B28 - Pinging/ Smog Questions

[DesertBMW]

all numbers are high, this indicate bad converter. Put back stock chip, and stock injectors and new cat converter, should pass then.

[efficient]

When the car is at operating temperature spray some carb cleaner around the intake side and injectors and see if the carb cleaner changes the way the motor acts. If it changes then you got a leak

[RCM3]

I'm assuming the engine has a chip in it? If so do you know what type of tune it is running? Your explanation of what it sounds like when driving under load sounds a lot like pinging, perhaps too much timing in the tune.

For what its worth though you can check the catalytic converter function with a lift and an infrared thermometer. The engine needs to be running and the cat needs to have been warmed up (like 10 to 15 minutes of driving should do). A functioning cat should run between 800-1200 degrees Fahrenheit and the downstream should be 100 degrees hotter then the upstream exhaust pipe temps. If the cat will not heat up or the pipe farther back is colder then the incoming air the cat is not doing its job.

A vacuum leak can cause a lean miss which would also produce those sorts of HC's however I would think knox would be lower.

The engine is chipped. I actually do not know the specifics on the chip nut it will be coming out tomorrow. Now that you mention it, after the install of the new ECU is about when I noticed this sound starting up.

Ill get the car up tomorrow also and get out the infared temp scanner. Hopefully this is the issue. Ill also do another check to find any potential intake leaks however during the tune up I replaced many of them including the intake boot.

Ill report the findings tomorrow. Thanks for the pointers!

[rommaster2]

I'm assuming the engine has a chip in it? If so do you know what type of tune it is running? Your explanation of what it sounds like when driving under load sounds a lot like pinging, perhaps too much timing in the tune.

For what its worth though you can check the catalytic converter function with a lift and an infrared thermometer. The engine needs to be running and the cat needs to have been warmed up (like 10 to 15 minutes of driving should do). A functioning cat should run between 800-1200 degrees Fahrenheit and the downstream should be 100 degrees hotter then the upstream exhaust pipe temps. If the cat will not heat up or the pipe farther back is colder then the incoming air the cat is not doing its job.

A vacuum leak can cause a lean miss which would also produce those sorts of HC's however I would think knox would be lower.

[RCM3]

Ive never had an e30 fail this miserably! Im going to go back through the vacuum system. But since the car runs and idles so well, I dont know if thats the issue. The car also is cooling well, it runs a the 25% mark on the gauge.

My last e30 didnt blow nearly the white smoke this one did when I SeaFoam'd it. This e30 smoked out the little valley my parents live in out in the country. Is the amount of smoke coming from the exhaust correlated with the amount of carbon material being removed? Ill have to research that...

[efficient]

Wow! Nox is sky high. Vacuum leaks raise nox aswell and also a faulty coolant system.
My friends 325 89 was blowing on nox aswell, we haven't figured it out yet but the car passed smog lol

[RCM3]

I just used some SeaFoam, 1/3 into the brake booster vacuum line, 2/3 into the fuel. Is repeating the process of introducing 1/3 pint of SeaFoam to the intake recommended/ effective if I do in fact have heavier carbon build up? The internet offers conflicting info.

I brought the car to one final smog shop and they wanted to do a deep engine clean (tech suspected lots of build-up based on a quick once over and looking at the smog results) and then suggested getting a new catalytic converter. The deep cleaning was expensive for what it was, so I figured Id run a cleaner through myself.

Then again, maybe the engine is still clean since it has seen very few miles since the rebuild? If the smog numbers werent so high I wouldnt be as worried and just replace the cat.

[RCM3]

ISSUE RESOLVED! New CPS fixed the issues.

Hello guys,

Ive done a good bit of research on this subject and have received advice from members in the past regarding smog on another M20 but this situation has a few new variables. The car would be a CA gross polluter but I did a pre-test thankfully. The emissions are pretty bad (see pic below...)

Background on the car:

I bought this e30 somewhat recently, this e30 has 128k on it and a fresh and expensive engine rebuild completed about 5 years ago. This e30 also is stroked to 2.8l done by the PO and has some bigger injectors installed (40 lb. Mustang? I think the PO said). I put in a chipped 173 ECU after I bought it. Everything else is OEM.

The car runs great, makes very nice power also. No idle issues or CELs. I just did an extensive update on the M20: timing belt, tensioner, water pump, O2 sensor, AFM, oil, oil filter, air filter, fuel filter, spark plugs, spark plug wires, thermostat, coolant hoses, BMW coolant, intake manifold gaskets, valve cover gasket. I run only 91 octane in it.

I have noticed at WOT (wide open throttle) when pulling a hill I sometimes hear a rattling from the engine. It happens once I put the throttle down and attempt to accelerate. The car shows essentially no changes in performance while accelerating, but makes this rattle sound, marbles in a tin can kind of noise.

Im wondering if this is related? Timing is spot on, maybe carbon build up from running very rich while the PO owned it?

I have stock M20 injectors or M50 injectors I can swap back in. I also have a stock 153 ECU and factory 325iS exhaust with a solid cat that passed my recently totaled 1988. Im going to change those items out, but is this enough to lower my incredibly high emission numbers? Is there a great product out there I can use to break up any carbon build up? Anything else I can look at to make this car pass smog?

The car has a 2012 sticker on it, so this stroker engine at one point passed smog. Local exhaust shops are booked up for weeks in the town my parents live in (where this e30 is currently). They all want to swap on an expensive cat, and while that might help lower the emissions, I dont think it will ultimately solve this issue without correcting a few other things

Thanks for any information guys.

-Ryan