View Full Version : sr20det wont idle, drive fine.

03-01-2012, 03:45 AM
I just got a s13 with an sr20 redtop, I fixed the MAF wiring before it was always in limp mode and ran like crap. Now it just won't idle, sometimes it will but sometimes it won't, doesn't matter how hot or cold the engine is it'll do the same thing. If it idles it will for a while then just drop down and bog then die. I am trying to figure out if it is a vacuum leak, the MAF, IACV, or could it be the TPS? I really would like to get this fixed, and on the boost gauge at idle it just sits at 20, but other then that the car runs fine not rich or anything.

03-01-2012, 04:31 AM
boost gauge says +20psi at idle? Im leaning to vacume leak. Get in the engine bay while its at idle and listen when you give it some throttle. Also get someone in the car to see if it drops back to vacume when you let off.
Where/ who did you get the car from?
Any mods?
How many miles on motor?

03-01-2012, 04:36 AM
Could be tps and a small vacume leak but if its running 15-20lbs vacume that's kinda normal or atleast its normal for my car but check the voltage on ur tps also if u have a safc u can go into the monitor settings and it will tell u what its currently running at should be at 4.5v I belive I had had a junk tps befor and my s14 sr ran the same way

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03-01-2012, 06:56 AM
I got the car from a friend a few days ago, I'm not sure how many miles are on the motor but it feels to be a strong motor, its just given me some electrical problems because whoever had it before me and my friend just kinda threw the wiring together. But its got FMIC, bov, top mount turbo, mines stage 2 ecu. But ill check the tps when I get home from school today, I gotta get a new multimeter my friend crushed mine one day on accident...

03-01-2012, 07:08 AM
Honestly if u know the harness is hacked I highly recomend buying one from wiring specialties they're the best I had some stumble issues and cldnt tune it away then I bought myself a harness from them bam it was gone worth every penny for a reliable plug and play harness. Its amazing

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03-01-2012, 07:17 AM
mines stage 2 ecu

I think your problem is here. do you have mines stage 2 ecu requirements ? I doubt it. Check this, and if you dont have what it requires, either get a proper remap or the missing components.

03-01-2012, 03:04 PM
Check your BOV for a leak at idle. I see it happen all the time.
Take a can of parts cleaner and spray around suspected areas of leakage. Idle will jump up if there's a leak and you spray it.

Swap in a for sure good known MAF to eliminate it. My coupe had a MAF that gave off voltage (albeit incorrect voltage) so my car would actually run, just not well. Didn't idle for shit either.

Also TPS voltage should be around .45-.55V when closed.
4.5V is for when it's wide open.

03-01-2012, 03:42 PM
Alright I'll check the bov, and I took the mines ecu off and put a stock code 62 ecu on and it did the exact same thing. My car runs so much better with the mines ecu , the stock one made it run really rich. But ill have to find someone with a good maf sensor cause no one I really know has a 240. But I'll be working with it today and see what I can find out and post back up what I find later. Thanks for the help

03-01-2012, 03:53 PM
check voltage on blk/yellow wire at iacv plug
if its low or dead hook it to swicthed power

03-01-2012, 08:34 PM
Ok well I just went and checked the TPS, It is .46v closed and WOT is 4.125v I know that WOT is kinda low but i don't think that would affect the idle would it? I also checked the black/ylw wire on the IACV and it was getting the correct voltage as well.

03-01-2012, 08:40 PM
also, forgot to mention, If I hold the throttle around 2k-1.5k rpms it runs really rich, the wideband is in the highs for rich and you can tell its running rich but once you get about 3k rpms it leans out and sits where its suppose to.

03-01-2012, 08:53 PM
unplug the TPS and run the car, see if the idle changes, if it idles fine in "limp-mode" then you'll know the TPS is the problem...

Basic Troubleshooting...

Running rich just sounds like bad o2, bad injector seals/injectors or bad tune...

03-01-2012, 09:17 PM
I have tried that, it doesn't change does the sme thing just affects the throttle response. I mean it doesn't run rich all the time just in the rpms that it won't idle at. It won't idle at anything under 2k rpms

Ok so I disconnected my MAF that I have on it right now, and when I got the car it came with 2 extra mafs, a q45 one and some other one I think its a KA24DE. So I wired up the Q45 one, it fixed the idle, it would sit right at 1k and not move,but it was running very rich and you could tell badly. The MAF that is on it right now, is a remanufactured one it looks new but do you think that is what it is?

03-01-2012, 09:40 PM
if iacv has sufficent volts check maf or wiring to maf
also did u check for leaky o ring on injectors
i gotta sr coupe at my crib right now that has good volts to ecu and sensors
but will not idle and it gurgles a bit wile reving below 3000 rpms
stock w a garrett t3..
it ran fine before someone swapped motor into car
i unplug maf it idles perfect....
so it turns out maf wire was fixed but that caused more of the issue
when they used some random wire instead of using maf wire to extend it
check over harness sensors etc

03-01-2012, 09:48 PM
Yeah I just finished checking the MAF and everything, I had wired up a Q45 and it fixed the idle problem but it also made the car run like shit lol It would idle perfectly at 1k but the car would shake and was running very rich could see black smoke coming out the exhaust and the AFR gauge was sitting flat at rich.

03-01-2012, 10:48 PM
You have a way to compensate your ecu for a large MAFS right?
You can't just swap out a different/higher resolution MAFS without proper tuning.

Go find/wire in a stock/known good SR MAFS

03-02-2012, 01:07 AM
Oh I know that, but the ECU I have is a Mines ECU, which atm I am not sure if it is tuned for the bigger MAFS or not. But I just did it to see if it would idle, the car runs poorly with the bigger MAFS but it also idles correctly, which means I am going to get a stock SR MAFS.