What do you guys think?Is it my MAF or ECU?(stock)I need some help on this one.

[redsx13]

Long story short, i had to remove my r32 maf, larger injectors, and tuned ecu and replace everything to stock in order to diagnose an idle issue. But after returning everything to stock the car seemed to have major problems. When the key was cranked, the car would start but only idle for about 5 seconds and then die. this would happen every time the car was started. If you tried to keep it alive by pressing on the throttle the car would instantly bog out and die.

I eventually traced the issue back to the MAF, When i unplugged the maf the car would hold a steady idle at 1500 rpms. But again, if you tried to give it some gas, it would still bog out and die. The rpms would not go up at all from 1500 with the maf unplugged.

thankyou for any help.




Modified by redsx13 at 12:43 AM 11/19/2008

[shift_SRDETuser]

Check voltage with a volt meter -- I have gotten pretty good with mine - having just installed my boost gauge .... The maf unplugged it will not rev past a certain safety level. I think JWT website has documentation on z32 maf wiring not r32 -- never really heard of any one running the r32 maf,....

[redsx13]

Check voltage with a volt meter -- I have gotten pretty good with mine - having just installed my boost gauge .... The maf unplugged it will not rev past a certain safety level. I think JWT website has documentation on z32 maf wiring not r32 -- never really heard of any one running the r32 maf,....

ya, people do run the r32 mafs, they are not as popular though, because the z32 mafs is easier to get ahold of in the US.

I have had a maf go bad on me before; on my ka. the thing just sounded like it had a rev limiter at 4 grand, and smoked like crazy. but thats not what my sr is doing. my sr wont rev up at all weather the maf is plugged in or not.

I would LOVE to check my maf with a volt meter, but..... I dont know what to check for! other than the fact that on the harness, the ground (Black)is ground and power (black w/white stripe)is 12 volts.


Modified by redsx13 at 11:25 PM 11/16/2008

[shift_SRDETuser]

ya, people do run the r32 mafs, they are not as popular though, because the z32 mafs is easier to get ahold of in the US.

I have had a maf go bad on me before; on my ka. the thing just sounded like it had a rev limiter at 4 grand, and smoked like crazy. but thats not what my sr is doing. my sr wont rev up at all weather the maf is plugged in or not.

I would LOVE to check my maf with a volt meter, but..... I dont know what to check for! other than the fact that on the harness, the ground (Black)is ground and power (black w/white stripe)is 12 volts.

Modified by redsx13 at 11:25 PM 11/16/2008

there are two grounds and hot side 12 volt power wire... There is also a signal wire that fluctuates with air -- make sure it is going up and down...

[redsx13]

What is the signal wire at idle (in volts)

[shift_SRDETuser]

What is the signal wire at idle (in volts)

rated at 0 - 5v so I would say someting like .5volts closed to 4.XXX fully opened should be right

[redsx13]

I tested my maf, the signal wire at idle is not even making 1 volt.

[redsx13]

rated at 0 - 5v so I would say someting like .5volts closed to 4.XXX fully opened should be right

what do you mean fully open and closed? its a maf not tps???

[shift_SRDETuser]

what do you mean fully open and closed? its a maf not tps???

voltage should be less than 1 volt at idle this is correct -- but it should go up with flow as the throttle is increase and air flow increases its signal voltage should increase as well.

[redsx13]

voltage should be less than 1 volt at idle this is correct -- but it should go up with flow as the throttle is increase and air flow increases its signal voltage should increase as well.

ooo... thanks, but i cant increase flow because i cant rev the car at all. If i give it gas, the car just dies.

tps?

[shift_SRDETuser]

ooo... thanks, but i cant increase flow because i cant rev the car at all. If i give it gas, the car just dies.

tps?

you can test the tps with the engine off. I do not think it is the tps though -- does it bog or just die. Sounds like a huge boost leak have you done a compression check and make sure the engine is ok then move on to piping....

[redsx13]

you can test the tps with the engine off. I do not think it is the tps though -- does it bog or just die. Sounds like a huge boost leak have you done a compression check and make sure the engine is ok then move on to piping....

With my r32 maf tuned ecu and injectors, the car wil actually run, it just has a really rough, rich idle (tends to search up and down for a few seconds after reving). tps voltage is 4.6 at idle, and 5.1 volts at wide open.

Compression is just about 150 across the board, i have checked for boost leaks a million times. how do i make a boost leak testor so i can check with that.

O...I should also add that I am only making 2-3psi boost!!!!

Is there a way i can check my actuator?

[shift_SRDETuser]

your tps voltage at idle should be .45 - .55 volts----

[redsx13]

your tps voltage at idle should be .45 - .55 volts----

I just got through messing with the tps, since it seemed like there were too many volts at idle, i spun the tps to compensate, but when i did, i found somthing really weird.

I found that my tps does not increase volts steadily as the throttle is opened(ex. 0volts-1volt-2-volts-3volts and so on) instead it jumps from straight from 0 volts to 4.6 volts and goes up from there. (for example, 1/4 throttle=.0 volts,1/2 throttle=.0 volts, 3/4 throttle=4.8 volts, 4/4 throttle= 5.1 volts

time for a new tps?

[shift_SRDETuser]

I just got through messing with the tps, since it seemed like there were too many volts at idle, i spun the tps to compensate, but when i did, i found somthing really weird.

I found that my tps does not increase volts steadily as the throttle is opened(ex. 0volts-1volt-2-volts-3volts and so on) instead it jumps from straight from 0 volts to 4.6 volts and goes up from there. (for example, 1/4 throttle=.0 volts,1/2 throttle=.0 volts, 3/4 throttle=4.8 volts, 4/4 throttle= 5.1 volts

time for a new tps?

could be wiring, could be the tps, could be the aftermarket ecu tune......good luck finding it....

[redsx13]

could be wiring, could be the tps, could be the aftermarket ecu tune

No, it cant be wiring or ecu tune. The tps is a variable resistor that works as a kind of potentiometer which transforms the Throttle valve position into output voltage and sends back that voltage to the ecu which in turn inteperates it along with the imput from the maf and the o2 sensor. The computer then does the mathmatical work between the three and sends out a certain voltage to adjust how long and at what time to open the injectors thus supying the engine with fuel. as long at the tps gets 12 volts and ground, its signal has nothing to do with the wiring or ecu at all.

but thanks for the imput
Modified by redsx13 at 12:58 PM 11/19/2008

[shift_SRDETuser]

No, it cant be wiring or ecu tune. The tps is a variable resistor that works as a kind of potentiometer which transforms the Throttle valve position into output voltage and sends back that voltage to the ecu which in turn inteperates it along with the imput from the maf and the o2 sensor. The computer then does the mathmatical work between the three and sends out a certain voltage to adjust how long and at what time to open the injectors thus supying the engine with fuel. as long at the tps gets 12 volts and ground, its signal has nothing to do with the wiring or ecu at all.

but thanks for the imput

Modified by redsx13 at 1:11 AM 11/19/2008

congrats you know how a tps functions and what its purpose is.. You are the expert sr20 owner.....

then why ask the question?-- you could have an open wire somewhere in the harness running from the ecu to the tps -- could be a number of things causing a volatge spike in the tps or making it not read correctly -- replace with a new one then you will know if that fixes it... I had a honda with a tps that would spike because of the tps gasket which had a break in it.....

oh and you would have been ripped to shreads if you would have asked this question on the zil forum.......
Modified by shift_SRDETuser at 6:29 AM 11/19/2008

[redsx13]

congrats you know how a tps functions and what its purpose is.. You are the expert sr20 owner.....

then why ask the question?-- you could have an open wire somewhere in the harness running from the ecu to the tps -- could be a number of things causing a volatge spike in the tps or making it not read correctly -- replace with a new one then you will know if that fixes it... I had a honda with a tps that would spike because of the tps gasket which had a break in it.....

oh and you would have been ri pped to shreads if you would have asked this question on the zil forum.......

Modified by shift_SRDETuser at 6:29 AM 11/19/2008

I apologize shift_SRDETuser, I didn't mean to come off conceited. I would never call myself an expert sr20 owner, if i was,i wouldn't be asking for help. To tell you the truth I have never even driven a car with an sr20 before. After my swap, i was faced with soo many problem that it has rendered the car undriveable. my 240 has been sitting for almost a year. 3 different shops, 2 different SR20DET's, 2 different ecu's, 2 maf's, four different injectors, a stripped block at the turbo oil line banjo bolt, a snapped exhaust mani stud, 2 new exhaust manifold gaskets, only 2 psi boost, and no idle.O ya, and one of the shops that worked on my car forgot to latch the hoodpins, the hood flew open, broke the window, and smashed the roof, they told me i brought it to them in that condition, and i got NOTHING from them! you cant blame me for being a little frustrated, and desperately in need of some advice.

[shift_SRDETuser]

I apologize shift_SRDETuser, I didn't mean to come off conceited. I would never call myself an expert sr20 owner, if i was,i wouldn't be asking for help. To tell you the truth I have never even driven a car with an sr20 before. After my swap, i was faced with soo many problem that it has rendered the car undriveable. my 240 has been sitting for almost a year. 3 different shops, 2 different SR20DET's, 2 different ecu's, 2 maf's, four different injectors, a stripped block at the turbo oil line banjo bolt, a snapped exhaust mani stud, 2 new exhaust manifold gaskets, only 2 psi boost, and no idle.O ya, and one of the shops that worked on my car forgot to latch the hoodpins, the hood flew open, broke the window, and smashed the roof, they told me i brought it to them in that condition, and i got NOTHING from them! you cant blame me for being a little frustrated, and desperately in need of some advice.

Instead of asking a bunch of questions and looking for people to answer you -- you need to search the forums and I mean there us quite a bit out there. The sr20det was also used in front wheel and all wheel drive cars. I know you are frustrated -- but you need to be smart with your engine and what you do-- learn what components do what and then get a benchmark start. If you never had the car running right to begin with then this could be a problem-- do you know how to pull codes from the ecu?

I feel you about the shops -- but unless you have a mechanic you trust which I have 1 guy in my area that I do then I would not let anyone work on my car. It is your car and nobody is going to work on it like you do.

[redsx13]

Believe me, i spend hours upon hours searching, and i never post until i do. I know there is a ton of information out there.

anyhow, i do know how to pull codes, but all i get is a 55. So it seems like my stubborn little sr wants to make me work for it.

The stock maf i bought has to be broken, because the car runs worse with it connected.

Because my sr barely runs with the stock ecu, injectors, and maf, i have decided to try an diagnose it with the aftermarket parts.

I think the reason why i i am having such a hard time is because there are multiple problems so far i have narrowed it down to

1. bad stock mafs (because car runs worse with it plugged in)2. bad tps (bacause car runs no different with it unplugged, and voltage and ohm tests come up "no good")3. bad actuator or vaccum line (car has low, low boost, and turbo checks out)