tabasco122

Ok, so i tried searching this site and others, i couldnt find anything anywhere that matched what issue im having, so if you find something, please feel free to berate me lol.

So I drove 900 miles from Louisiana to Indianapoilis for the 3000GT/Dodge Stealth National Gathering. I dont own a 3s anymore, but im still friends with all of the people and i go to the gatherings. Upon pulling into the parking lot of the hotel (after a 14 hour drive, pretty much straight), my car started surging really bad. At idle it goes from 2500rpms and drops down to 1500 then drops back down again. It does this constantly.


Things i have tried.
1. boost/vac leak test. Made a tester from pvc and stuff from lowes, pressurized the system, found a leak, fixed it, still no change.
2. unplugged the tps
3. ordered and bought a new tps from oreilly (97 200sx)
4. unplugged the maf
5. unplugged iacv
6. pulled codes (came back 55, all clear)
7. Hooked it up to NDS to see if i can see anything strange, nothing.


The funny thing is that it looks like the ECU is turning off the injectors, causing it to go full lean (21.8 AFR) thats when the idle drops down from 2500-1500, then the ecu starts firing the injectors again once it gets down to 1500. so basically the afr just keeps on bouncing between high 14's and full lean.

One more thing im going to try is plugging the IACV and the hole where it goes in the intake pipe and seeing if that changes anything, if it does then its probably just a broken iacv, but unplugging it did nothing.

tabasco122

i should probably add that its a fully built sr20det, currently running stock turbo and fuel. also stock intake manifold.

Bbsalexaz

honestly I don't think its the fuel system, I think its the ignition track. Maybe a dieing ptu, or a bad o2 sensor in combination...

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sean350z

Whats the timing when surging? Whats the voltage at the o2? Whats your coolant temp sensor reading?

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tabasco122

PTU is possible, but i would figure it wouldnt go full lean if the injectors were still firing. Stock O2 is deleted, using the innovate wideband analog out to the ECU.

Timing, i dont remeber, it differs depending on the rpm as it surging. coolant temp sensor is almost identical to my aftermarket gauge.

Ill hook it up later and get you guys that information.

tabasco122

ran a 13.7 @ 102 at the track tonight. still having the issue, not sure exactly what it is. i have a spare ECU at home i can try, but that wont be till monday.

danceNdrift

My car isn't boosted or an SR for that matter but i'm having a similar issue. I found that I have a blown intake manifold gasket. maybe check that?

tabasco122

Its brand new, but ill try to get my hands on oem stuff when I get back.