engine runs pretty good. it does have a pretty large exhaust leak on the pass. side. but its throwing codes 22, TPS voltage low, 33, MAF signal high, and code 44 everynow and then which is 02 sensor is low...

its a new-used TPS, MAF and a realativly new O2 sensor...

i'm guessing the exhaust leak is messing with the flow of the engine and throwing everything off?

the first 2 codes i've ALWAYS had though. even when this exhaust leak was pretty minor...

 

Is the TPS adjusted to 0.54 volts??

 

I believe the TPS out of whack can cause a MAF high error.

I would reset or replace it as necessary.

Do a complete IAC TPS setup procedure located here in the tech articles, than clear the codes and see what happens.

later
Jeremy

 

well i went STEP BY FREAKING STEP from the manuel that i have. only problem is, when i put everything back and started the car the engine idled at 1600!!! i had the minumum idle at around 500 when i was setting it...

so i just turned out the idle screw got it down to about a grad and reset the TPS to .54 volts as its always been.

i also cheaked the operation of the TPS. it works fine, a nice even upping in voltage as you slowly open the throttle. no dead spots either.

ok so i got the idle down and all, but now i have code 21, and the engine hunts when i come to a stop. i also went to move it this morning for my dad and it didn't want to start. i had to crank it for a bit while giving it gas. and even then it didn't run right at all...

what is code 21 all about? i know it has to do with timeing, that connecter for the computer controlled timeing IS re-connected and all...

so in short, i got rid of those 3 codes, (as far as i know anyway, i had it idleing for a couple minis and then went for a ride around the block, thats when i noticed it hunting for the first time) but now i have code 21 and the engine runs like crap!

 

Code 21 is tps voltage high.

 

o thats right. yea i read it somewhere else about that and i guess i put the two together in my head? iono...anyway. any ideas guys? i really need to get this truck up and going again ASAP. any tests i could do?

 

Truck? MAF? Your sig has 84 S-15, What are you working on?

 

yea...i did an engine swap...the engines from my brothers camaro...

 

Well code 21 will cause driveability issues. Recheck TPS at idle and do a full sweep. Make sure TPS goes back to initial setting each time you sweep test.

 

Make sure you have proper grounds none of your sensors will function correctly, you will be poppin codes like no tommorrow.

 

i didn't think this mattered but 2 wires were swapped with the TPS connecter. i asked my brother about it he said he never touched the harness when he had it in his car. but the guy before him scrwed all with the MAF and fuel pump releys. so i'm assuming it was his doing. pins a and c were switched. so i cut and soldered them back together. could this have done anything to the computer or fried anything?

and thinking back, my dad broke my brothers MAF when ripping it out of the car from my brother having the timing 180 off and it caught fire when this engine was put in the camaro. haha. you couldn't tell which way the connecter went in, and i always thought it went in the opposite way it does now. it was all fused but you think that did anything either? i got a new MAF as stated i think before, and the connecters in right and all but yea...

 

well i've set the tps at .53 now and it's still throwing the code. its hard to start too. you have to give it gas...

i also cheaked that ground again along with a couple others and there all fine....

it only throws the code when it idles below about 1200 or when crusising on the highway.

this thing also takes a while to idle down to the 900 or so that it should idle at. it'll stay up at around 14, 15 hundred or so for a while then all of a sudden slowly idle down to 900. but it takes a while. blipping the throttle a bit helps sometimes though.


i'm thinking about throwing all this TPI crap out next saterday and getting a carb....whudda think?

 

How are you checking the TPS voltage? Scan tool or volt meter? Next you need to look at the parameters for setting the code, you may have a tps code because of something else. Your MAF may be messed up, reading air flow when there isn't any as a possibility. Do you have scan data? Post if you do.

 

no sorry i've been useing a voltmeter. i'll have acess to a scan tool tommoarw in my auto class. i'll set the TPS voltage that way. is there anyway i can cheak the MAF if its good or not? last i cheaked it did have the 3 wires in it.

what do you mean by scan data?

 

well alright, somethings wrong with the schools scanner and it doesn't work right. it said RPM's were 5600 at idle and the TPS voltage was 1.04 volts no matter what position it was in...

still same code, number 21, but now you have to give it gas for it to start????

also, unless the schools timeing light is screwed up too, it won't run at 5-6 degrees advance. according to the timing light is was probably about 20 degrees advance where i had it. but i timed it, it ran like crap but w/e, i drove it home, had no power, firing out the exhaust leak, so i advanced the timeing just by sound and yea, runs smoother and seems to have more power(didn't go for a ride). so i figure its the timeing light...

my teacher had my old TPS still laying around so i figured i'd stick it in there. didn't change anything. if anythings its worse. going to stick the other one back in to see if it'll at least start without giving it gas...

at this point i would like to just scrap the whole TPI thing unless someone can tell me whats wrong. i'm guessing its the TPS, MAF, computer, some, or all of them...

 

Sounds like a ground lead, wiring harness, or ECM problem.

My personal vote would be to yank the harness out and check each lead... not just the ones involved. Then compare your harness to a chart to be sure you have every involved ground lead - and when you reinstall the harness, make sure that the surface they are attached too has minimal paint or is paint/grease free.


Sounds like the harness has lived a hard life already.

 

I've don a couple TPI swap/installs now and I can't stress enough to check, double check and check again to make sure all the grounds are right/make a GOOD connection. Also, you were setting the timing w/ the esc unhooked, right? - Next, what's you fuel pressure at, and what's your vaccum at?

 

i re-did that ground for all the sensors even though it was fine. i took a wire brush to the firewall and the connecters. fuel pressures at about 48 without the engine running 35 with the engine running. i look over EVERY wire for the TPS and MAF. only problems i saw was a little bit of corrosion on the connecters for the computer(cleaned em up real nice and put some engine assembly/electrical greese on em), and the wires are pulling out of the releys for the fuel pump, and MAF. there still makeing a great connection. a long time ago i took each connecter apart and soldered them so they wouldn't pull out aynmore. so i KNOW its a great connection...

so now what? MAF or Computers shot? i cleaned the MAF, nothing.

it still needs gas for it to start, its idleing high, and if it does go down to a somewhat normal idle it throws the number 21 code. i tried re-doing the idle AGAIN...nothing new...

i tried the scanner AGAIN and cheaked all the wires for the ALDL, nothing. wires were fine, scanner works worth a crap...at least on my truck. think maybe the ECM's shot and not giving the right data to the scanner?

if i do buy an ECM should i get just the computer, the chip, or both? would you trust buying an ECM or MAF from ebay, junkyard, or new? i really don't wanna go new...

 

I think you may be looking in the wrong direction. Look at the parameters for setting code 21.

1. TPS voltage is greater than 2.5 volts for at least 2-5 seconds.
2. Airflow less than 12 gm/sec
3. Engine speed less than 1200 rpm

So with this in mind, is it possible that the MAF is dropping out and car starts to run like crap so you hold the gas pedal down to keep it running---

1. Your TPS is over 2.5v
2. Airflow is less than 12gm/sec
3. Engine speed is less than 1200 rpm

This is just a scenario that could happen. I'm not saying it is, but if you think its possible, then look at the MAF.

I'm not positive, but on some GM cars when the MAF died, you could disconnect it & run the car, it would actually run better, thus confirming the MAF was bad.

You don't have any air leaks between the MAF & throttle do you?

 

anyway i could cheak my MAF? i saw a test on one of the posts and according to it everything cheaked out ok... no i have no vacum leaks, i already looked at that. even disconnected all the non-neccesary vacum lines, pluged em, and nothing new...

only way i could see that scenario happening is if when i give it a bit of gas to start it. but still, its not running. other then that i don't touch the trottle, and the engine idles down by itself...and the code doesn't come on until it idles down...

remember how those 2 TPS wires somehow got switched on me? what could that have done? anything to the computer? its a new TPS so it didn't fry that...

 

I wish I could tell you how to check the MAF with the tools you have, but I don't know how. I use a scan tool for diagnostics. Maybe someone has a test sequence for a Voltmeter type test. My gut feeling is a bad MAF or MAF circuit. As far a vacuum leak, I wanted to point out that the boot between the throttle & MAF can't have any cracks or leaks that would cause a low MAF reading. Try running the car with the MAF unplugged. What have you got to lose? Look on ebay for a MAF they have to be out there, I've paid $10.00 when I have needed them.

 

the boots fine, it runs HORRIBBLE with the maf disconnected. i tried that earlier tonight . yea but i don't really trust the MAF's on ebay...especially if someones selling one cheap...i guess maybe i'll go any try to convince the local junkyard to let me hook one up, if it works them i'll buy it? i don't know how well that'll go though seeing its an electrical part and all...

 

well i found 2 things out today, i somewhere got a hypertech chip put in my computer??? and its not the computer or MAF. 87tpi7749 sent me a "new" computer and MAF and it didn't change anything. still code 21.

would that hypertech chip have anything to do with it? i would assume so...

also, iono why, but it was running really bad at one point, i D/Ced the MAF and nothing changed. engine stille ran rough. i turned it off, turned it back on, ran fine and ran horrible with the MAF D/Ced. i'm thinking these 2 year old releys are gone for the MAF. seeing there only what? 10 bucks maybe? i'll get new ones. but still, what about that chip?

 

Check wires at tps. Pin A=ground, Pin B=signal return, Pin C=5V pos with key on. Then check back at ecm pin C13, this is the ecm input from TPS, It should show the same as at the TPS. If this is good, you have to get scan data or you are gonna replace alot of parts before you find the problem.

 

You really need to get another scan tool on there somehow. At this point your in the dark without the ability to find and verify what the PCM is actually seeing.