Pulled codes on my 92, some quick questions..

[plethaus]

I just bought the car in my sig and it runs basically flawlessly, except that the CEL is coming on at random while driving and it has a slightly rough idle. Other than that it runs strong and smoothly right up to redline. I pulled the codes to see what was up...

I did the full sequence of tests (KOEO stored codes, KOEO tested codes, KOER, KOER cylinder balance test)

Here's what I got.

KOEO stored codes:

511 - No power to PCM pin 1 or bad PCM (processor)

KOEO tested codes:

172 - Oxygen sensor not switching - system is or was lean - Single, Right orr Rear HO2S - Fuel control
176 - Oxygen sensor not switching - system is or was lean Left or Front HO22SSS - Fuel control

KOER codes:

172 - Oxygen sensor not switching - system is or was lean - Single, Right orr Rear HO2S - Fuel control
136 - Oxygen sensor not switching/system lean Left or Front HO2S - Fuel control
411 - Idle speed system not controlling idle properly (generally idle too high) - ISC

And the cylinder balance test:

2 - Problem with cylinder 2
3 - Problem with cylinder 3
4 - Problem with cylinder 4
6 - Problem with cylinder 6
---------------------------------------------------------

Ok, so obviously I need new O2 sensors. Can shoddy O2 sensors cause a car to idle rough but otherwise seems to run OK? I'm not too sure about the 511 code and the 411 code. The guy I bought the car from said it has a Superchip in it, so I'm thinking that might be the cause of the 511 code. What do you think?

The 411.. what does that mean? What can I do to fix it? I'm guessing it's related to the rough idle problem.

As for the cylinder balance test - dirty injectors maybe? I remember reading somewhere that the cylinder balance test is performed by the computer adjusting the fuel being put into each cylinder and then recording the differences in RPM..

What are your thoughts?

Thanks

 

[SASHO91]

New O2's...
Clean the IAC (Idle Air Control valve) -- behind the Throttle body...(code 411)
and IIRC, yes the chip will cause that code-511

as for the cylinder balance test... im not sure.... clogged injectors would be my first thought. second would be a bad coil pack OR DIS module... but you say the car runs to redline fine... weird...

i would pull the superchip, and reset the EEC. Then go take the car out for a day and see what pops back up.

BTW, not many people have luck with superchips. In fact most that run them end up having problems...

 

[SuperHO]

511 is caused by the chip...either toss it, reset yer puter and drive on or simply ignore it. if it's a generic superchip, it's a piece.....I've got a custom tune that aside from makin it run rich as **** is a marvelous piece of technology.

Other than that, what he said.....

 

[plethaus]

How do I take off the Superchip and reset the computer? I bought the car with it so I don't know how it was installed.

Also, how do I clean the IAC and where is it?

 

[Mr Anonymous]

New O2's...

NO! NO! NO! NO! NO! NO! NO! NO! NO!

YOU DO NOT NEED NEW O2 SENSORS!!!

plethaus, your codes clearly indicate that you have a vacuum leak somewhere.

The fact that both O2's are showing lean is the first clue. Both sensors almost never fail simultaneously, and both sensors showing the same condition indicates that the motor is in fact running lean.

The second clue is the 411 KOER code. When unmetered air is entering the intake tract it can raise the idle of the car beyond the point where the IAC valve can properly control idle. In many cases, the PCM can command the IAC fully closed (which would normally stall the motor) and if the vacuum leak is big enough the car will keep running.

The third and final clue is the cylinder balance test results. Now normally your test results might suggest an issue with coils 2 and 3 in the coil pack due to the suspect cylinder numbers, but here with the other codes presented, it suggests that cylinders 2, 3, 4, and 6 are not firing properly due to an overly lean mixture in the combustion chamber.

So, what you need to do is figure out where the unmetered air is coming from. It could be something as simple as a loose intake coupler, disconnected or damaged vacuum hose or a rip/hole in the convoluted hose from the MAF to the TB, or it could be a problem with the mating surfaces between the intake and the heads. Has the intake been off the car recently?

If after looking things over if nothing jumps out as an obvious source of the unmetered air, get yourself a can or two of carb cleaner at your local parts store and with the engine idling spray it around the various connections along the intake tract, including where the intake meets the heads. When you observe an obvious change in idle quality, you have isolated your vacuum leak.

 

[plethaus]

*snip*

Hmm... I will have to check this out.

Here is something weird the car does, maybe it's related? And also it may be normal, I don't have any experience with SHOs, so...

When I start the car when it's cold, I can hear a very strong rush of air that sounds like it's coming from the air intake (the previous owner strapped a K&N cone filter directly to the MAF) - whoooooooooooooosh.

After the car gets up to operating temp it seems to go away, but I can still hear it slightly.

Also, the previous owner did have the intake off (he painted it).

So where do I start...?

edit: Here is a picture of the engine bay and the cone filter setup:

 

[CerberuS]

Get a stock air box with a K&N panel filter.

Cones are crap , it fuzzes the MAF , and you suck all the hot air from the engine (not good)

The stock air box is more performent then that piece of crap.

If you need one i got one handy.

 

[plethaus]

Get a stock air box with a K&N panel filter.

Cones are crap , it fuzzes the MAF , and you suck all the hot air from the engine (not good)

The stock air box is more performent then that piece of crap.

If you need one i got one handy.

I know what you mean about the cone filter. I think it's stupid and way too ghetto. I just don't know if it will fix the problem (going back to the stock airbox)

In any case I sent you a PM about it.

Thanks

 

[CerberuS]

replied.

 

[SuperHO]

If the intake was painted, check everywhere you may think a gasket goes and make sure a gasket is in fact there. Are your secondaries opening at 3950 rpms?

 

[plethaus]

If the intake was painted, check everywhere you may think a gasket goes and make sure a gasket is in fact there. Are your secondaries opening at 3950 rpms?

Yes, from what I know about the secondaries they seem to be opening properly at 3950. I will goose it a little during my lunch break and see what happens for sure though.

Will also try looking around for obvious vacuum leaks... I really hope it isn't the gasket between the heads and the manifold or something.

How hard is it to dismantle the manifold to inspect those couplers that connect everything together? I've read they get dry and brittle/cracked on high mile cars and cause vacuum leaks.

 

[SuperHO]

not that hard...just time consuming...

The gasket between the head and the manifold is the easiest to change out of all of the gaskets it could possibly be, except for the throttle body gasket....

 

[CerberuS]

kit is cheap too : http://home.earthlink.net/~rcm_automotive/index.html

 

[SuperHO]

So, umm, what MAF is that? It ain't stock.......

 

[plethaus]

So, umm, what MAF is that? It ain't stock.......

It's an 70mm one, at least that's what I was told.

edit: fixed, meant to say 70mm

 

[SuperHO]

If it were me (and I've been in your shoes before after leaving the friggin gaskets between the runners and plenum off), I'd go through and look at every spot where metal touches metal and verify that there's a gasket smooshed in there. It's easy to spot, cuz even the meanest of wrenches ain't gonna squeeze the gasket into non-existence. Check the throttle body to intake, runners to intake and check to make sure the hose from the intake to the fuel pressure regulator (silly lookin thing stickin up from the fuel rail near the crossover tube) and another hose in the back that hooks up to the intake and goes down into the abyss behind the motor.

 

[plethaus]

Thanks, I'll finally have some time tonight after work to mess around with it a bit and I'll see what I can find.

 

[plethaus]

Well I'm in the middle of going around looking for vacuum leaks with my eyeballs and a can of carb cleaner. So far nothing, except this from the intake elbow:

If you can't tell it's a small rip/hole in the intake elbow about the width of a pencil or a little smaller. I'm not sure if it would cause a leak though because it would be tightly sealed against the metal of the MAF (you can see the rub marks from the MAF in the second pic, it goes past the whole)

Otherwise I am about to try a stock MAF that came with the car and see if it runs any different. After doing a lot of searching on vacuum leaks it seems that a dirty MAF element can cause a lean condition, and given that the idiot previous owner strapped an oiled K&N filter directly to the MAF I can see it get fouled up pretty easy..

 

[plethaus]

Well that wasn't it.. the search continues.

 

[SuperHO]

have you pulled your intake apart yet?