seta 2.7i starts wont idle when hot

[AlphaE]

Hello,
I really tried searching the webs and here and I hate posting. I'd rather figure it out my self. but im stumped..

Basics: 2.7i from seta. green top 17.5 inj, full swap. ECU 173, cam, valve springs, oil passages, intake, TB and AFM.
Never really idled super smooth after sway but good enough. PROBLEM- car will start instantly, goes to 1k as norm, comes down to normal idle and just keeps dropping,chugs and barely catches, surges. DIes, instant resart, same idle.

Last week: Thurs when cold, first thing in AM, starts and runs fine. Get to partial warm up, shut off. Restart, instant start up but idles like crap. then clears up 2mn later and runs as usuall. Gets full warm, shut off. Restarts instant but crap idle. clears up.
SATURDAY, starts and idles like nothing was wrong. gets warm and idles a bit rough as norm. Drive for 20mn- full warm. Turn it off, it sits 15 min and instantly starts but idles for crap. Throttle doesnt really help, choughs and sputters though till something clears up and then runs fine.
think its maybe Leaking injectors??? so I swap back to the seta injectors. Disconnect batt. reset ecu. Starts right up and idles/runs great. Take it out and romp on it some. SHut it off. restart 10mn later, runs fine.. great, its fixed...
SUNDAY starts and run fine in am..... drive 25 min, shut off. Restart, idles and runs fine. drive another 35mn park for 3.5 hrs, starts right off but stumbles some. smooths out. Drive 10mn, resart, idles like crap, then clears up. Drive 20mn, eat chipotle, instant start, crappy idle, clears up fast. on to Gander and Walmart. Starts instantly each time but idles poorly longer. Drive the 40mn home restart instantly after shut down and runs fine. Wait 45, instant start, poor idle, but it clears. Go for another errand shut down, wait 10mn resart runs super super crappy, cant even drive it. Get a 1222 code- thanks for nothing motronic:(

Disconnected batter to reset ecu- doesn't help
Disconnect O2, runs even worse. O2 is ok.
Swap ICV- no difference
Swap Fuel Reg- no difference
Swap AFM- nothing.
work in garden 2.5hrs
DO smoke test, fix one SMALL leak.
starts instantly idles poor but better, clears up. Take out and flog. Normal power through entire RPM. Turn off wait 5, restart and everything is good.

THIS MORNING- am-instant start and runs like BUTT!!! Disconnect CTS and instant idle change, smooths out, drivable. Let get to temp, idles better than ever, shut it down. Restart 2hr later, instant start, crappy idle. same things through out morning.
AT LUNCH-
PUll off vac line to FPR and squirt starting fluid in as its chuggin and surging. IT HELPS
Suspect fuel pressure- its ok
Notice if I floor it will rev perfectly but wont idle. Revs all the way to 5-6k. comes to idle and crapps out.
suspect TPS- swap and adjust a good one- NO DIFFERENCE
swap CTS- nothing
Swap FP and 02 relays- nothing.

Possibilites I can think of:
Head gasket- BUTt would still run like crap after sitting over night vs 2hr. and it revs fast when you get on it hard even at rough idle. Not to mention it instantly starts, goes to 1k then comes down like it always has. Coolant would be a long crank and sputter to life I would think.
CPS- BUT it starts instantly ever time.. plus if it decides to clear up and run, everything works as it should.

DIGGER and Jvlie and FF HELP!!!!!!

[AlphaE]

and.. I was running a 154 ecu for a while and it did it once on that ecu. but had NO worning. Just go out at end of day and it idles for crapp.. Swap in the 173 and life was good till now...

[jlevie]

PUll off vac line to FPR and squirt starting fluid in as its chuggin and surging. IT HELPS

That makes me think of intake leaks. I realize you said that you smoke tested the engine. The correct smoke test is to plug the exhaust, replace the AFM with a plug that has a nipple for smoke introduction, introduce oil smoke until a pressure of 2-4psi is reached, and hold that pressure for at least 5 minutes. Was that how the smoke test was conducted?

[AlphaE]

not exactly..... I had done it that way about a year ago right after doing the "I" swap, and it was all good. I cheated and just removed afm and used the right plug in the boot and just smoked it up.. no exhaust plugged used. I kinda doubt its a vacumm leak, cuase it will run fine at times. both cold and hot... I just noticed that it wont hold any RPM when its acting up. not 700 nor 1200 nor 2000.. but it will rev smoothly from 1k and up w the peddle.. I just did it and eventually the idle worked itself out, but its far from fixed. just more observation....

The lean, does make one think of an intake leak though.....

guess ill make time to smoke it again...

what else causes lean?

[jlevie]

It is essential that the exhaust be plugged, that a plug/nipple be used to replace the AFM, that oil smoke (long persistence), and that smoke pressure be held for at least 5 minutes to allow smoke to work it's way to leaks far from the intake. Several small leaks, far from the intake, can add up to a serious leak.

Do the smoke test, properly, first. If no leaks are found, I'd replace the DME as the next troubleshooting test.

[dnguyen1963]

Check the aluminum elbows going into the throttle body. It can get loose and cause crappy idle. It can then tighten up under engine vacuum and the car drives without any issue. This cycle can repeat and give you lots of headache. Smoke test can miss this problem if the elbows are in a "tight" position. If you can wiggle the elbows then it is time to put some JB weld around it.

[AlphaE]

Check the aluminum elbows going into the throttle body. It can get loose and cause crappy idle. It can then tighten up under engine vacuum and the car drives without any issue. This cycle can repeat and give you lots of headache. Smoke test can miss this problem if the elbows are in a "tight" position. If you can wiggle the elbows then it is time to put some JB weld around it.

Interesting...... Seems plausible... Will smoke test in am. Ours doesn't have a psi gauge.. I rarely use it. I'll have to see. It has a smoke , .004, .002 and a few other settings. So .004 would be more pressure and show a smaller leak while .002 lower pressure would only show major leaks, from what I can figure out. That sound right?

RE:o2 sensor, there is continuity on heater circuit and 13v from the car while running. BUT.... would a crappy o2 do this? The po says he replaced it and It looks new but the car also had a plugged fuel return line when I bought it. Pegged fuel pump like 80psi and a CEL Aka MAJOR RICH afr! Could a dead or messed up o2 be the culprit?

I do remember it acted like this one random time last winter then straightened out the next day.. Now it's hanging on to whatever the issue is now....

[AlphaE]

Started it after work. Hadn't been started in like 2hrs. Fires but idles poor. Rev it from 1-2k for a bit. Drive 100yrds and it idles fine.... Take a little drive. All is well. Shut off and instant restart, good to go. Park at shop over night.

Got a feeling it won't idle in am.....

The o2 is making more and more sense... Kinda...

Thanks for replies already!!!

[AlphaE]

started and idle rough but not the HEAVY surging like before.. It seemed to smooth out a bit also, but I didn't want it to warm up before I smoke it again..

dumb car...

[dnguyen1963]

I let my car fully warmed up before smoke test. That way I can find all the small leaks that might be sealed when the engine is cold.

[AlphaE]

our smoke machine doesn't work like that Jlevie.. but as far as I can tell it is good. there is a small leak out the shaft on the TB. but I'm not gonna mess w that..

while it was idling like crap after a hot start, I swapped in a a 153 "I" ecu and it surged from 1-2k very steadily.. I put in the 154 supereta ecu and it didn't surge but ran similar to the 173. so I put the 173 back in... and it was kinda better..

as usual it smoothed out and I took for test drive and it was fine.

this am, it started perfect, idle ok to good. I pulled it out and the idle got real smooth as it warmed up.. I started it 10mn and 1hr later and it was normal both times..

WHAT THE HECK!!???

Im gonna put the green tops back in and see what happens..

I checked leak down on FP and it was golden
I want to check again, but the o2 sure seems fine as well
I replaced the FF and it helped other issues but it still idled wacky sometimes.

love hate relationship goin on here....:(

[jlevie]

our smoke machine doesn't work like that Jlevie.. but as far as I can tell it is good. there is a small leak out the shaft on the TB. but I'm not gonna mess w that..(

I don't understand that statement. If your machine lacks a pressure gauge, tee one in to the smoke output hose.

[AlphaE]

I rarely use it so I don't know for sure. we mainly use it for evap systems, so I think its regulated down a lot. I put our shop air 130psi in and when I put a gauge on the FPR line I only saw like .05 bar.. it wont go higher.. so I carefully put some shop air in to increase the PSI and then the flow ball on the sight on the smoke machine dropped out.
so I smoked it for a while, then added shop air... IS there any tolerance for leaks?? I really don't wanna mess the TB shaft.. itd need a new Tb and who's to say the junkyard one doesn't leak. Seems there should be some tolerance for small leak... or i am totally wrong...

while I did not do exactly as you said im pretty dang sure its not a vacuum leak issue. this am it ran mint even w the small leak at the TB I saw last night. im sure the leaks I saw last night are still there now and its running fine..

I noticed the coolant lines never had pressure and tank cpa never hissed when I open it.. A new tank cap is ordered and shipped already... there is NO WAY that's the problem... Is there....????

[jlevie]

.05bar is only .7psi. Good enough to find evaporative system leaks, but not enough pressure for finding intake leaks.

The fuel system on an E30 has a filtered vent via the charcoal canister, so it won't hold pressure or vacuum.

[AlphaE]

Well.... I think it was good enough.... And also...... I may be retarded... I'm embarrassed to even say I work on motors and equipment all day.... But I think I fixed ... Do your maintenance people. I pulled the wire off the coil and the entire end busted off in the coil... The problem did seem heat related and coils do get hot. I rigged up a temp fix and it's running good so far. Only been a day, but seems to be fixed.. Can figure how it worked out though.. Maybe there was a gap that as things expand and contracted with heat would cause it act up.. Sure seemed fuel related though... Hope that was the problem, it sure is gonna help things over all..

Maintenance people.. Learn from my, " if it against broke, don't fix it" frustration...