Zutz23

Tuned Performance

iTrader: (92)

Zutz23

Tuned Performance

iTrader: (92)

If you have converted to speed density get one for a 90-92 tpi. 85-89 tpi is maf.

Zutz23

My 87 has both a MAF and MAP sensor. I replaced the MAF. I need a MAP sensor

Tuned Performance

iTrader: (92)

You must be running a 411 ecm

Zutz23

Tuned Performance

iTrader: (92)

87 doesn’t use a map it must be left over from a carb baro to tpi swap.
Or someone put on a speed density plenum.

Zutz23

Tuned Performance

iTrader: (92)

Good luck finding a map, no map here !
http://chevythunder.com/maf_code_33.htm

Zutz23

Zutz23

Tuned Performance

iTrader: (92)

Now your getting it no map

Zutz23

Drew

iTrader: (58)

MAP or MAT? One is an air temp sensor, the other is an air pressure sensor. Other heat related sensors that you actually would have would be ECT - Engine Coolant Temp, which is fairly important.

Zutz23

Zutz23

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Tuned Performance

iTrader: (92)

Sounds like you might need to get more involved or educated on what’s going on. See if he’s fighting a code 23 or 25.

Tuned Performance

iTrader: (92)

There are 3 lines for vacuum
1) for brake booster
2) for fuel pressure regulator
3) for hvac

Zutz23

Tuned Performance

iTrader: (92)

I’d pull the car from the shop codes for Maf high and maf low.
http://www.chevythunder.com/maf_code_34.htm

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Pro

If its a map sensor issue which it doesnt sound like, its the same part as the one on the GM trucks, which are everywhere, including new at the parts stores

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Vader

If this was originally a carbed engine there would have been a MAP. Carbs were available in '87. As has been stated earlier, if it had been swapped to TPI there might still be a MAP on the firewall - unnecessary, of course.

It would help a lot to know what ECM is installed.

Zutz23

Go Blue

It sounds like when the engines were swapped that it went from a carb with a MAP sensor to a TPI with a MAF sensor, but the engine computer (ECM) doesn't recognize the MAF. It's still looking for the MAP readings which this fuel injection system doesn't use. Sounds like you should either tell Tuned Performance what ECM you have (the mechanic can tell you if you ask him. It sits behind the kick panel by the passenger's feet). Tuned Performance is one of the go-to guys on here for ECM/tuning information. With the part number from that he can probably tell you if you need a different PROM chip or ECM or what. That would be my next step. I'm used to be a certified mechanic but i've let my certs go and stopped working in that field except on the side. I have agreed with everything that Tuned Performance has said. 1 of those 2 sensors can go, but since the MAF came with the fuel injection system, I would stick with that rather than the MAP sensor.

Tuned Performance

iTrader: (92)

I’m guessing you have a 1227165 ecm, Diagnoise the maf issue to see if it cures the rich condition. Another factor once the maf codes are fixed you might check the body of the injectors to see if they have been swapped from 19#hr to 22#hr. If they have been swapped and the ecm still has a 305 chip in it . That would cause it to run slightly rich.

Zutz23

Go Blue

Tuned Performance, excuse my possible brain fart, but if they add bigger injectors that would add more fuel. Adding more fuel would mean that it would be running a richer mixture correct?? He's already saying that he's running rich. He would want more air to lean out the mixture. Or have I just been out of the game too long and i'm swapping rich and lean in my mind?? Plus, he stated that he already replaced the MAF and nothing changed. I still think that the ECM is searching for the MAP readings because it's the wrong ECM for his new engine that has the MAF on it. Would he need to replace the ECM or possibly just the PROM chip?

Tuned Performance

iTrader: (92)

If they swapped out the injectors with 350 injectors 22#hr.
The ecm might be programmed for 19#hr 305 injectors. This would cause a rich condition.
He might have a bad ecm. I would start with the trouble tree for 33 and 34 codes and see where it leads. I have heard of guys running a 305 chip and even 19#hr injectors on a 350 without a issue although that combination would be a lean mixture.
Sounds like the mechanic might be talking about the mat or iat same thing just different names. This is located underneath the plenum in the rear. Iirc a low air temp would be a richer mixture. It’s hard to say what’s done to the 350 or if the suffix and casting are really from a 350.
I would check that out before throwing parts at it like injectors or a tune.you would be able to tell if it has a tune in it bye the letters on the prom or if it’s a Hypertech the part number.

Go Blue

Ah. Ok. Thanks for the reminder. I can see how that could cause a rich condition now. There's definitely too many factors that could lead to this. I hope his mechanic is willing to deviate from only wanting to replace the MAP sensor and check these other things.

Tuned Performance

iTrader: (92)

I hope so to. The last thing he needs is a mechanic who is a parts changer.
You might need to find another shop or learn to diagnose it yourself.
Lots of good comments and suggestions on this thread. I would suspect the ecm but that’s just a guess following the flow chart would be the best bet.
If the mechanic watches the grams per second at idle to see the maf airflow it should be 7-9
Grams per second.
Code 33 sets when flow exceeds 45 gps below 2k rpm and 1/4 throttle.
The ecm has a 5v pull-up on the signal wire. If the signal voltage is 2.2v or higher for 1 second code 33 will throw.

Go Blue

I'm still wondering if the ECM even sees the MAF sensor or if it's still waiting for the MAP sensor to show something??

Zutz,

Did this just start happening or has it been happening since you bought the car? From what I have read, this car had an 84 carb with a MAP sensor initially and you (or the last owner) swapped in an 87 350 TPI setup?? If that's true, did the 87 setup have a MAP or a MAF setup when it was in the last car? If so, I doubt that the ECM is even looking for MAF as it wouldn't know what it or how to read it because it's expecting to see a MAP sensor and use its reading in terms of how to richen/lean out the fuel mixture. If I remember correctly.

Tuned Performance

iTrader: (92)

Btw if the ecm has a service number of 1227730 it would use a map not maf.

Pro

This would all be solved if someone (including mechanic) would just yank the computer from the dash and have a looksee lol

Zutz23

Vader

Look at the vehicle's VIN. If the eighth character is "G" it was made with the 305 4BBL (lG4) engine. Lots of those were made, and many of them were for Canada.

Vader

If your mechanic can find a MAP on the intake of a stock '87 TPI I'll buy lunch for BOTH of you.

He's apparently confusing the LT1 with the TPI. I have both, so I can understand his confusion/lack of memory.

Zutz23

Go Blue

Zutz23

Zutz23

Go Blue

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Go Blue

This would be a good time for Tuned Performance to chime back in since he knows a lot more about codes than I can remember off the top of my head. I would want to see a troubleshooting chart for that specific code at this point. Have you tried googling that code to see if there's a flowchart online? You might also find more people with that code on here if you try searching for it.

Go Blue

Did you replace the MAF or did the mechanic? If the mechanic did it, ask him if he still has the original sensor. If so, look through the middle of the sensor where the air flows, do they look the same? If not, there's a possibility that the new sensor doesn't use a burnoff relay and the wiring is slightly different. I just read that in another thread. The other question I would ask him is if he checked the IAC sensor as that seems to be another possible culprit. Do a search in the "TPI" forum for code 33. I found several threads about 5-10 down from the top that had some info. I'd still like to see the diagnostic flowchart for it though.

Zutz23

I have the sensor so I’ll check but literally I did all that work and the problem hasn’t changed