88 TPI Stock

My main issue usually occurs in traffic or if the car heats up over 220 at a stand still. Below 2000 rpm the Engine will stumble like fuel is being cut off too it and I have too keep on the gas too keep it from dying. It will surge and stumble.

Check Engine comes on once in awhile when I slam the gas when this happens. I can't get a reading using the paperclip trick, I think the wiring has been jacked around on this car.The Check Engine light just stays on, Pin 6 and 12.

I have a fan switch installed so I keep it below 220 at all times. Now this occurs more often when the engine is warmer, but it will act up when running between 200-160.

This usually happens randomly, I can drive it all day long with out much issue. Other times it will act up more when stop and go starts happening.

Diagnose these symptoms for me someone?

 

Take your car into a parts store that will check your error codes for free. I know Auto Zone will do this. After that and you got your error code, come back on here and tell us what it is.

Also, are you doing the error code check correctly, the paperclip goes between pins 5 & 6. The trick is you need to be able to identify 5 & 6.
Try this method one more time.

It sounds like the ECM is in limp home mode.

 

It almost sounds like the ECM is running on the backup chips. You might want to check out the MEMCAL seating/connection and the harness connectors at the ECM. Power down first, of course.

EDIT: ARGHH! Doc beat me to the punch.

Anyway, in this diagram, jumper terminals 'A' and 'B' (ground and diagnostic request):

 

Hey I truely appreciate it guys, will follow up on all of this and report back my findings. Thanks.


* Strange ok, Code 33 is what I get, Driver side fan turns on too when I ground B and A. What in the **** lol, there must be some kind of wiring issue there on top of the code 33. Hell maybe the cause of it... I think someone tapped the block thermal sensor for the fan into the ECM ground? Not good? blah I don't want to trace wires, it is 30 degrees outside.


33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor).... hrmm

Only found a few post dealing with this code, one of them is from you Vader. and I'll quote it here

"The 33 error code will put you in limp home mode, that is why the engine runs so crappy when the SES lite comes on due to a 33 error code.

Dosconnect the negative battery terminal and wait 2 to 3 minutes, then reconnect. This will erase the error code. Then warm up the engine and shut it off. Now do the idle speed IAC setting routine found on this board.

Also, check the TPS voltage at idle, it should be less than 0.64V.

Drive the car around and see if the error code is gone for good"


Is this still valid for an 88 TPI, the original poster was questioning about a v6 90 Firebird I believe.

 

Sorry about that VADER. BTW: tyridar, you should be very glad to see that Vader is involved with your post.

You have the dreaded 33 error code. What causes the 33 error code?
If all three following condition are met at the same time, you will set the 33 error code and the ECM goes into limp home mode:
1) engine under 2000 RPM, 2) MAF reads over 45 gms/sec flow, 3) less than 25% throotle.
I use to have this problem, it was the most fustating thing. The only way that I got rid of it for good was to burn my own Eprom chip.

A slightly modified 350 TPI will have this potential problem. If I run in OD on the xway, I would set this code at will. So before I learned to burn my own chips, I learned to drive the car in D, and shift to OD when I got the car over 60mph. That way, I avoided conditions number 1 and 2 from occurring together.

And BTW: you can erase all error codes by disconnecting the negative battery terminal for 2 to 3 minutes.

 

Yes, that is still valid. Make sure the TPS is set correctly and even toward the higher end of the allowable range (right at 0.63V or so).

Or, as Doc and I have found out the hard way, skew up the MAF max range tables.

You're actually more fortunate that Doc has taken an interest in your problem. He's all over the ECM nuances and intricacies.

 

Hmm thanks guys, when the weather clears up, I should be able to make some progress and will report back.

About the radiator fan coming on when I ground 5 and 6 to check the code. What in the hell? Not good? haha Is that suppose to happen?

 

My fan comes on whenever I would clip out across A and B terminals as shown in Vaders diagram. I believe that its supposed to. dont worry about it. I have read error codes 100 times, and never having the fan come on hurt anything. If the fan did not come on, I think that would mean that you have another problem.

 

Im getting codes 33 and 34 now with my 86 firebird v6. Now, whats the "speed IAC setting routine"? Thanks

 

The ECM runs a relay test when the diag resquest is jumpered, this just tests the ECM's ability to drive the relay to ground.

 

Update*

I erased the error code. I have been driving it for the last 2 days, attempted to simulate the issue again, no problems as of yet, seems to run fine. I think this error code happened when I first drove it home. There was a bad ground wire for the electric fans which I fixed after testing. It overheated at one point though in traffic. I wonder if this set the code off. Interesting. Weather is not permiting me to do anything further, crappy crappy. I need a damn garage.

You guys need to bump heads and write a thousand page tech support book for 3rd gens with the knowledge some of you guys have. You might make some money. It would put Chiltons and others too shame.