85 iroc check engine light - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 9 (permalink) Old Sep 9th, 02, 07:58 AM Thread Starter
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From: newport news va
Registered: Sep 2002
posted 09-07-2002 01:25 PM
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Please help. I posted this is electrical and wiring, but I think I put it in the wrong forum. So I reposted here. Hope someone can help.I bought an 85 IROC 305 TPI 700 R4 tranny. Got it home and rebuilt the engine. Bored 30 over upped the cam but stayed computer friendly. Put 194 valves in. Turned the crank. Started the car and had a few codes. Ran the codes and replaced the MAF, and the MAT. Started up and got an O2 sensor bad (44). Replaced the O2 and started back up after a min of the car running good got a 44 again O2 sensor. If I shut down and restart it runs good again for a min then hunts up to about 2 grand and check engine light comes on. Code 44. I never put the smog pump back on and I capped off the manifold with plugs, along with the breather tube for the cat. The car has great pick up. If I stomp it the car throws me in the trunk even with the engine light on. However it runs rough and hard to idle at a light. Check engine light at idle in drive is 400 or 500 to a stall, off is 750. Any ideas? Thanks for your time and any help.
Jeff



drew69
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From: Kingsland, Georgia
Registered: May 2002
posted 09-08-2002 06:31 AM
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Welcome Jeff,
Is the MAF installed correctly? Don't laugh I've seen them installed backwards (upside down) there should be an arrow on it indicating air flow.
Code 44 is a lean exhaust not always O2 sensor.

Are you using a scanner or jumping the connector and reading "flash" codes?

What kind of vacuum reading are you getting at idle?

If you have a scanner does the ECM go into "closed loop" operation?

With a scanner, what kind of "fuel trim" values are you seeing (they should be around 128).

Post more info.

Drew


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post #2 of 9 (permalink) Old Sep 9th, 02, 08:05 AM Thread Starter
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I checked the MAF, its good to go. My vacuum reading at idle is 10 to 12. I was using a scanner at first and it was going into a closed loop. I dont have access to the scanner any longer so I cant check the fuel trim values. Also I sprayed carb cleaner on the engine in a few spots where I thought I might have a vacuum leak. The engine changed idle when I sprayed the bottom of the plenum runners. Passanger side. Could this be the entire problem?
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post #3 of 9 (permalink) Old Sep 9th, 02, 08:21 AM
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Greetings 85iroc,

I had an 85 Z28 with a 305 in it some years back and had a similar problem with the code 44 coming up. Changed out two of the O2 sensors. Went to the dealership and had them check it and they told me the same thing. Something didn't seem right so I asked to borrow their maintenance manuals. After doing some (a lot) reading, I asked them to humor me and adjust the throttle position sensor. They put the scanner on it and found the tps was about 4 millivolts below the minimum. After adjusting it to the proper voltage, the code 44 went away and never came back. It's just a thought but you might want to check it out. Good luck!!!!!!!!!!!!!!!!!!!!


The Trickster!!!!!!!!!!!!!!!!!!!!!!!!
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post #4 of 9 (permalink) Old Sep 9th, 02, 09:05 AM Thread Starter
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I never thought about that, I forgot to mention in my first post that I also changed the TPS. If its brand new should I worry about it?
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post #5 of 9 (permalink) Old Sep 9th, 02, 09:14 AM Thread Starter
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I would just like to say I realy appreciate any and all comments, Im anxious to get this car on the road. Thanks

Jeff
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post #6 of 9 (permalink) Old Sep 9th, 02, 02:01 PM
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Jeff, the Trickster brings up a good point.
How to check your TPS without a scanner.

You'll need a DVOM. Key on, engine off (sounds like a [email protected]@D thing, huh?).
Anybodys three wire TPS will have 1 wire with a 5 volt signal from the ECM, 1 wire will be a ground, and the last wire will be the output (back to the ECM). Take a couple of paper clips and back probe the connector while it is plugged in to the TPS. Don't pierce the wire insulation just slide the paper clips (straighten out) down the wires till they touch the terminals. Using the DVOM determine which wire is which.
If you have an adjustable TPS watch the DVOM as you move it and set it for .450 to .490 volts. I would shoot for the higher end if you have a mild cam in it.

You really need somebody good with a scanner to help you out here but we will try to work you through it without hurting your check book!

Cheers, Drew

[This message has been edited by drew69 (edited 09-09-2002).]
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post #7 of 9 (permalink) Old Sep 9th, 02, 04:24 PM
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Greetings 85iroc

Sorry, in my first post I forgot to welcome you to the site. So, welcome to the site. There are a lot of great people here who are more than willing to share their knowledge and experiences with those that need it. In your second post, you mentioned that the idle changed when you sprayed the bottom of the plenum runners on the passenger side(I must have been daydreaming about my '85 Z28 when I was reading that post ). What was the torque value that you used when you tightened the bolts down? It should be something like 13-25 ft. pounds. I usually torque mine to about 19 ft. pounds to seat the gaskets, let it sit for about an hour while I work on something else and then do a final torque at 25 ft. pounds. Hope this helps!!!!!!!!!!!!!!!!!!!!!!!!!!

The Trickster!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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post #8 of 9 (permalink) Old Sep 10th, 02, 12:42 AM Thread Starter
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I just want to tell everyone thanks for helping, everyone here is good people. This was my first experiment with building a car engine. Although I have been an engineer and a mechanic for 15 years in the Army. I work on Detroits, I thought I knew all the important tricks. I was reading another post about the carb cleaner on a vacuum leak, I tried it and I found the leak. I guess you learn something new everyday. So anyway to the point I tightened the Plenum to 23 lbs in three passes. I didnt wait an hour or anything but I did make three passes. The problem was I got a bit lazy. I used the old gaskets the first time around for start up because I didnt want to waste a new set. I knew I would have to go back in. I changed all the other ones eventually but never changed the bottom passanger side and thats what was leaking. I changed it last night and it has a nice steady idle. No engine light. Runs great. So thanks everybody. One quick question. Whats the easiest and CHEAPIEST way to determine HP? I had a few estimates of 300 to 330.

Jeff
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post #9 of 9 (permalink) Old Sep 10th, 02, 04:29 PM
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Jeff,
AHH SOO, Yep diesels don't have vacuum unless you add a pump. Can be very tricky on a gas engine, huh?

Good to hear you've solved this problem.

I guess you are at Ft. Eusteis ?

I worked in Norfolk & VA Beach for a few years from 95' - 98'. Don't miss the traffic or 64 (now called the inner loop ?) one bit , ,

I lived in NC right over the line from Chesapeake a total of 38 miles from NOB, Norfolk. I will never forget the time it snowed over a layer of ice !!! It took me 3 1/2 hours to get home. The state police stopped counting accidents at 200 on the radio traffic report. Man, I was pissed and vowed that would never happen again.

Hampton Roads is hurtin' for roads !!!

Morale of the story, IT WILL NEVER HAPPEN AGAIN and my brother lives in CA and I don't ever plan on living out there either if my salary was trippled!!!
BTDT

Chow, Drew
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