87ColdAirIroc-Z

i have searched through many posts and tried many things. i replaced all the relays and there are no wire shorts. I didn't replace the MAF because i didn't find anyone who solved their problem w/a new MAF. I also think if the MAF was bad the SES light would always be on. please help?

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87 Iroc-Z 305 TPI
Dynomax exhaust
modified MAF & airbox
3-10" JL subs
Eclipse components

rondubbs

is the tps within specs???
i got rid of my 33 with a new maf.

Guest

Check for vacuum leaks, loose connections between the TB and MAF, and make sure the TPS isnt set too high. Corroded/loose wiring can sometimes cause it as well.

Glad you didnt replace the MAF yet, too many people jump to doing that and in my experience its rarely the problem.

MikeInAZ

I'm thinking the answer is in your signature "modified MAF & airbox". It's extremely easy to screw up a MAF and if you replace the MAF power relay and still have a 33 (be sure to disconnect the battery for a few minutes before rechecking) that it would be your MAF.

Also you say modified airbox. What part are you calling the airbox? Officially the airbox is between the MAF and the rubber TB bellows but I've heard people call their air cleaner cannister the "airbox".

If it's your air cleaner cannister you have modified that may be your problem if the 87's are like the 86's. You can't slice holes in them like some people do on other models.

Even a fairly small vacuum leak will set a code 44 so it seems your having a MAF related problem.

drive it

iTrader: (1)

If its intermittant do the "tap test". Lightly tap on the maf while the car is running and see if it sets the 33. A lot of times the maf will start going out intermittantly. Also check your tps volts at idle and the iac counts. If your throttle blades are not adjusted right you will set the code off and on while driving;if its way off you'll set it every few blocks! I run my iac at about 30 counts after warmed up. I con't to have that problem with more airflow in my engine combo. and took care of it in the bin.-burning my own chips. The code sets if the ecm sees greater than 45gm/sec. under 2200rpm and less than 1/4 throttle. Hope this helps.



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86 406

88IROCs

"I also think if the MAF was bad the SES light would always be on"

not necessarily, read this month's "Magnum TPI" article in GMHTP.

87ColdAirIroc-Z

I have tried all of these things. I may not have replaced the power relay; which one is the power relay. and is the burnoff/power/and fuel pump relay all the same part #. Explain what you modified in the bin to change the iac counts to set off the SES light?

drive it

iTrader: (1)

You adjust the throttle blades until the iac counts are about 30's. The bin change is in the ecm constant table-its called MAF high diag. threshold. In tunercat just move the slider up from 45gm/sec. I put mine at 125 and never see the code now, but if the maf fails it'll hit 255 and still set it if needed.The fuel relay is a diff. part # on the y cars-and some books list diff. part #'s and some list the same for the maf burnoff and power relays-I've used the same part # and never had a problem. Hope this helps.


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86 406

87ColdAirIroc-Z

Thanks i will try these things hopefully one or both help