chucacabrawow

I have an 89 camaro 2.8l v6, and i've been having problems with the idle speed bogging down and engine stalling when i stop the car at a red light or stop sign. I read a bunch of post where the IAC had been readjusted and fixed the problem. So i went and hooked up my winaldl to the car in diagnostic mode and got a reading of 50 counts for IAC in idle -

Now im no mechanic but is it possible for the IAC to be this high?

Just wanted some clarification in case i was reading something wrong - thanks guys

Maverick H1L

iTrader: (8)

First, remove the valve and clean it. That usually helps in a lot of cases. Second, make sure you don't have any vacuum hoses broken or deteriorating, as the MAF system dislikes unmetered air entering the engine and throwing off the A/F mixture.

My FSM says between 0 and 80 counts is acceptable. Lower numbers meaning your idle is too high and 80+ being too low. Check the counts with the engine off. They should be 140 or more, for easier starting.

What is your idle speed with the engine at operating temp? For the T5, it should run about 550-650 RPM, and 700 RPM for the 700R4 in Drive. Also, using the ALDL software, check your Block Learn... Should be about 120-125 if everything is okay. Lean is more than 138, and rich is less than 118.

Also, the book says to check your oxy sensor in the exhaust for contamination and old age, and replace if necessary. Better yet, maybe a complete tune up would help.

chucacabrawow

Thanks for the quick reply maverick,

I was going to clean out the IAC valve today but its been way too windy, if the weather is better tomorrow i will do that. As for the vacuum leaks i thought that might be a problem the car was having and ive been trying to find any by spraying starter fluid at suspected spots but havent found any leaks.

IAC count with engine off is 130 - with engine on it stays around 54 +-2.

Idle speed with car at operating temp (200f?) is 1100. in drive the idle speed goes down to 950

Im getting 2 error codes - 42 o2 lean and 34 MAP low

I took a pic of winaldl while the car was in park -


http://img511.imageshack.us/img511/3728/idle.jpg

Also heres the datalog i took of the car while in park -

http://www.mediafire.com/?ghtnyx4bivm

bob quint

By looking at your freeze frame data it looks like your map sensor isn't responding such will cause poor performance and stalling on stops because the PCM sees 0 v. Form the map if acts like it's running at 25,000 feet. This will cause a lean condition and detonation. Your iac seedms to be operation fine at 54 counts. If it were at it's maximum of 255 counts and u still had a low idle you can suspect a vacume leak or a bad sensor. Beyond that I would give the throttle body and iac valve a good cleaning

Maverick H1L

iTrader: (8)

You see the BLM number in your WinALDL pic? That is also referred to as the Block Learn counter. To add to what the guy is saying above, your BLM count is 142, and according to the manual, that means you're running lean.
You don't have a MAP sensor, which was used on carbed and 90-92 V6 cars in the 3rd gen. I'd check to see if the fuse on the passenger's side frame rail (with the red and the brown wires) is blown, as that is dedicated MAF feed. Also check to see if the relay is working by swapping it with the fuel pump relay and seeing what happens. Otherwise, you need a new sensor.

:edit: Also noticed in the pic that your TPS reading is high. You should elongate the mounting holes and adjust it to where it's supposed to be at .55VDC. It could give you problems later.

chucacabrawow

Thanks guys - good to know that its just the MAF sensor, ill go and check out the fuse and relay tomorrow; be back with an update.

chucacabrawow

alright - today i went out and tried to find the fuse you are talking about but i just could not find that thing. i know that theres a brown wire that runs to an in line fuse, and i tried to follow it but it looks like it just disappears? lol so after about an hour looking for the fuse i got fed up and ran down to autozone to try out a new MAF sensor - it didnt fix the problem, im gonna go check the relay later today and hopefully find that fuse.

Maverick H1L

iTrader: (8)

Those 2 fuses on the frame rail are the ones you are looking for. The one with the red and orange wires is for the fuel pump and the ECM constant power supply, and the other is the MAF fuse. I don't know why that brown wire is so long, but it is. The relay is tucked into the corner behind the air cleaner housing, attached to the end of the radiator support (or it's supposed to be attached, anyways).

chucacabrawow

Thanks Mav, ill go see if i can find the fuse. I checked the relay- its good.

One thing though that has been buggin me today is that there are NO clamps at all on the air intake house, also none where the MAF goes into the plastic intake (not sure what its called... its above the radiator) Im guessing that there is SUPPOSED to be friggen clamps in three places, and that its the root of my problem. Any thoughts on that?

Maverick H1L

iTrader: (8)

There NEEDS to be clamps there. It has been proven that any breaks in the air box between the air cleaner and the throttle body are likely to kill the MAF. How, IDK, but it's happened to me.

chucacabrawow

****!!!!!! so pissed... i finally found that fuse, and its good, then i went to lowes and found some awesome plumbing clamps that fit the intake hose perfectly. Those didnt help... then i was going to start the car up to show my friend the problem, and BAM!!! the damn coolant line from the engine blew... hot coolant everywhere. never seen that happen before, but now i have to go get a new hose from autozone and replace that.

Back to the idle problem, i was going to hook up winaldl again and get a log of the car when it bogs down again.. till then any other ideas on what the problem is?

*edit is it possible to run the car without MAF, could i just unplug the sensor?

Maverick H1L

iTrader: (8)

That would be the next thing to try. You can unplug the sensor and see if anything is different with the way the engine runs. However, I guarantee that if you have bad mileage now, it's only going to get worse.

Check to see if you have any loose or corroded terminals in the connectors, including the ones under the dash at the ECM. You might want to get some brake cleaner or something and clean all of the factory dielectric grease out of the relay connector as well.
After that, the only other thing is to check the resistance of the wires to see if you have a broken signal wire to the ECM. Check to see if you have power going into the MAF in the first place from the relay, and to the relay from the battery and wherever else it comes from, and to see if the relay is switching by holding or placing a finger on it as someone switches the key on and off without starting the engine. You should feel the relay click as the ECM switches the ground.

Maverick H1L

iTrader: (8)

I just remembered something. If you PM me your email address, I can send you a scan of the diagnostic charts for your code 34 in a PDF.