87 IROC Idle/throttle problems

[mavman70]

Hey all! I have a 87 Camaro IROC with a fuel injected 305. It doesn't run very well at all. The longer it runs, it seems, the worse it gets. It used to run fine, but then started having issues. I feel I must mention that the vehicle was my girlfriend's (now wife), and had been abused by her ex. I test drove it down the interstate, and it acted like it was suddenly out of fuel, bogging down and stalling out. I nursed it home again, and checked it over... the coil was loose from the firewall, spark plug wires were melted and shorting out on the headers, temp sensor wire wasn't connected. I had it going good for a few weeks, then it started having issues with the idle and throttle. It is now relatively good at idle, but bogs and chokes when I turn the throttle. I adjusted the timing over and over to no avail, and the fuel rail is getting fuel. I still need to check the actual pressure, but I did check the TPS, and it seems to work just fine. I hesitate to replace the MAF sensor since it is $150. ANY OTHER IDEAS???....PLEASE!!!! I am not that good with fuel injected motors- give me a carb any day of the week.

[Morley]

First off, is the check engine light coming on when it acts up? Does the light work? If no and yes....I would look into changing the coolant temp sensor. It is on the front of the intake manifold and is the smaller of the 2 devices there. They cost $7 at Advance auto and take 15 minutes to change.

Did you adjust the timing correctly? On these engines you disconnect the single brown wire with black stripe back by the firewall. It will be coming out of a large wire loom, has a black connector then it goes back into the loom.
Disconnect this, start the car, block the wheels and set the park brake. Set the timing to 6* BTDC. put back in park, shut down, reconnect the wire (called the EST wire BTW). Go to the battery and look at the positive lead. There is a smaller wire coming off of it, follow that to the fuse holder mounted on the fender lip about a foot away. Remove the fuse (ECM & fuel pump fuse) let it sit for a minute and reinstall the fuse.
Start the car and see what it does now.

If the check engine light IS on... Get a paperclip, straighten it out then bend it in a U. Stick the ends of it in pins A & B (top RH 2 pins) of the ALDL connector (by driver's right knee). Now turn the key on but don't start the car. There will be lots of clicking and the fan will kick on, normal.
Watch the check engine light, it will flash out the codes starting with 12...like this flash.......flash..flash. It will do that 3 times then move on to any stored codes and flash each of them 3 times. Once it has flashed out all of the codes it will start all over again with 12.
Post any codes you get here...If you get any MAF codes...DO NOt replace the MAF first.

[malletslinger]

When checking/adjusting the timing, if the white line seems to move or jump around(the line should appear to be stationary if the EST wire is disconnected and you are not making adjustments to the timing) then it is time to replace the timing chain, sprockets, and tensioner/guide.
This is a normal maintenance type of repair, (like a spark plug but not as often ) This is not a job you can do in one evening unless you have help from someone with experience, have all the right tools, and none of the bolts are seized
If you do it your self, it will probably be less than $100, if you have a shop do it, expect to pay much, much more. Id say a minimum of $300, and that would be a good deal.

[wrightz28]

Definately check for codes (EFI systems can be your friend).

But, what is the condition of the spark?

Otherwise, I'd say pull the throttle body, take s a few minutes, and clean it out thoroughly. While apart, reset the pintle one IAC, it hsould be no more than 1 1/8" from base to end.

Fuel filter would be a cheap insurance too

[mavman70]

Okay...First off, thank you to everyone responding! I have never been on a forum before now and was wary of using one or if anyone would even respond, again thank you! I feel bad for not having check the site sooner than now.
Alrighty then, Yesterday I hosed out the throttle body with Seafoam and decided to change out the TPS, just in case. The new TPS did nothing. I have ran the service codes, but all I got was 12, 33, and 36. But I had the whole air cleaner assembly off at the time. This morning I went out and hosed the throttle out again, put the old TPS back in and returned the new one. When I restarted, the throttle was working fine. I thought it was fixed, but as soon as I put it in gear, it quit. I restarted it and gave it some gas, which made it post detonate ("backfire" out the tailpipes, not through the intake). And it was now idling very badly, but off idle was great. It seemed to be running rich, so I was trying to adjust the distributor when I realized that the cooling fan was not operating. I shut the motor off, and tracked the wiring from the fan to a manual switch in the dash...nice, huh? After waiting for the temp to go back down again, I tried to restart, but the idle was so bad it just quit. A friend suggested replacing the idle control valve, so I did (no, the pintle wasn't too long) but it didn't do anything except cost money. It now starts up and just quits immediately, unless I start giving it moderate amounts of throttle, to which it responds with the "backfiring" out the tailpipes, until I let off, and it dies. SOOO....what does this sound like? I going to purchase a fuel pressure gauge and check it. What should the psi be? about 35?
Oh, btw...my wife told me that the engine was a crate motor that the previous owner had given to her with the car. It was installed without a timing tab and the wiring is a mess. I had to adjust timing the redneck way of turning the dist back and forth untill the best idle was acheived, I know it's not right on, but it should be pretty close...enough to run anyway! Also there isn't any fuel filter on the block, the line come up from the frame rails, into a rubber line, and into the fuel rail. I am going out to check if there is a filter down below somewhere, and to check the pressure in the rail.
Thanks Again for all of your time and advice! -dave

[malletslinger]

Code 33 = MAF Sensor..."Poor electrical connection, open or short in circuit; defective MAF sensor; defective ECM"
Code 36 = MAF sensor burn-off circuit..."Poor electrical connection, open or short in circuit; defective MAF sensor burn-off relay; defective MAF sensor; defective ECM"

You are lucky, you now know exactly what is wrong. Go to Napa or some other local auto store and get a new Mass Airflow Sensor relay, disconnect the battery for about 30 sec., reconnect it and try to start your car. If the problem isnt gone, then you need a new Mass Airflow Sensor that is expensive. I got a reman MAF sensor by Cardone and it works good, I found the best price at Parts America. It is a diff. MAF for your camaro, more $$$, but chances are, the best price you will be able to find it for is at the same place I got mine.
Part No.
744712
At http://www.partsamerica.com a Cardone MAF Sensor(reman) for an 87 camaro with any of the V8 packages is $144 with free shipping, there is a $95 core charge but you get it back. The part # is 744712, it is the most inexpensive MAF they sell but they are all remans and they are all made to work the same.
Depending where you live, it will be between 1 and 5 days to ship(hopefully one)
A bad MAF or MAF relay can easily be the cause of your problem, but people are always weary to suggest it because finding out you have a bad MAF is bad news $$$$$$$$$$$
Sorry I had to be the one to tell you.

BTW: Remember to try changine the relay first, hopefully that is the problem...remember to disconnect your batter like I mentioned before, that is how you reset your computer and clear the codes, if eather of those codes come up again after you change the relay, then change the MAF sensor. Im almost certain that partsamerica will be the most inexpensive way to get your sensor, its cheaper to get things off the NET.

Now go and make your I-ROC ROCK again!!!

[malletslinger]

Oh yea. I forgot to mention that your fuel filter is under the car on the metal fuel line comeing from the tank, you will need to jack it up from the rear to get to it.(rear drivers side)

[Morley]

Change BOTH MAF relays. One is MAF power and the other is MAF burn off.

[malletslinger]

Are you shure about that Morley? Im looking at a wiring diagram right now and I only see one relay for the MAF in the 89 and earlier 5 and 5.7L TPIs...the BURN OFF RELAY.
The 2.8s also have one relay for the MAF...the aptly named MASS AIR FlOW RELAY.
Are these diagrams wrong?
It probably is just the MAF, those are known to be short lived...

Here Lies
MAF
RIP

[mavman70]

Hey guys! Only problem is that I had the whole air intake assembly disconnected at the time (I was hosing out the TBI), including the MAF sensor...so it wasn't plugged in at all. That's why I wasn't surprised to see the 33 and 36 codes-it wasn't seeing the MAF at all! I have since plugged everything back together and reset the codes by disconnecting the batt. Only code that comes up now is the "you're in diagnostic mode" -code 12. Got busy last night with other issues, so I still haven't checked the fuel pressure or filter. Hopefully I can get to it later this morning before work. Thanks again everyone!

[Morley]

Originally Posted by malletslinger

Are you shure about that Morley? Im looking at a wiring diagram right now and I only see one relay for the MAF in the 89 and earlier 5 and 5.7L TPIs...the BURN OFF RELAY.
The 2.8s also have one relay for the MAF...the aptly named MASS AIR FlOW RELAY.

Quite sure, there are 2 relays for the Bosch heated wire MAFS (found on the 350 & 305 TPI's) They cost around $17 each. Code 33 is almost always generated by a bad MAF power relay and 36 by the burnoff relay. You should ALWAYS replace the relays as a pair because if one is bad, the other is the same age and will go out soon after.

The 2.8's only have 1 relay, MAF power, because they are not a heated wire design. They use a thin film that measures frequency when the air flows across it.

[wrightz28]

Doesn't 33 also point towards a TPs voltage problem?

[Morley]

Originally Posted by wrightz28

Doesn't 33 also point towards a TPs voltage problem?

Code 33= MAF sensor voltage reading high. Codes 21 & 22 are TPS codes.

[malletslinger]

How long ago was the crate motor installed?
The way you described everything melting and shorting tells me that the probelm you are having must be electrical and related to the engine control system...unless of course the problem is a clogged fuel filter.
Did you check all the relays in the engine compartment for damage? What about all the wiring in the engine compartment? inline fuses?
Is there anyone in your area with an 87 IROC you could put next to yours to compare everything and find out what the problem is. Could also be good for saving money while checking for the problem...an example might be that you could temporarily swap components like the MAF sensor, or the distributor to see if that fixes the problem, as opposed to going off and buying a replacement for each possible cause of the problem.

[wrightz28]

Morley,

I 100% believe and endorse anything you tell anybody, you know your stuff, no questions asked, with the upmost of respect.

However, in the troubleshooting chart when I was diagnosing my car's problems and had a 33 one of the break off charts pointed to a possible low voltage signal off the tps which ended up being the case in part.