Super Rich/No Idle..Okay High RPM

[KASilvia90]

Alright I'll make this simple, clear and descriptive but short and sweet also. I tried searching and nothing really matched my problems or I just didn't search the right thing, but I did search for over 2 hrs so please no nagging. I have a 1990 240SX with a KA24E M/T (But using an A/T ECU as I did a swap and never converted over)

History:Approximatly 7months ago my nice modded KA threw a rod due to having a blown headgasket get way to problematic way too fast on a 20mile drive home. I had a 150-shot of nitrous on a stock fuel pump and I believe it just went too lean, it learned from a mistake and have also learned a lot since then.

My old KA -with more than 150k miles but it could be a million, it was stuck on 151xxx when I bought it and I easily added 50k- went back in just recently. It had the dreaded timing chain failure, I cleaned it up and since I was flat broke and barely afforded the swap I used the 7k mile used timing components from my other KA. I am using the original head and manifolds but the injectors, rail and other things from the blown motor. I basically combined the two into one engine. The motor was in decent shape other than the timing chain failing, didnt burn very much oil at all just a little when it was cold and accelerating fairly hard.

Mods:It had a lot of modifications done to it and I feel I should list them to better help you help me: Complete emissisions removal, as in no egr, aiv or any of that kind of stuff. I only have 3 vacuum lines (FPR which has a solenoid bypassed and runs direct manifold, Brake Boost and Idle Air). Cold Air Intake, Open race header at the moment, ASP Pulley, Gutted Manifold (SCV's removed), Blaster Coil, Magnecor Wires, M/T Swap (it was an automatic when I bought it) but its still on a stock A/T ECU for now, E-Fan, Powersteer removal. Thats about all I can think of, at least that might alter some answers.

What it is Doing:It refuses to idle at all. All of the spark plugs are carbon fouled horribly, its running very rich like when I rev it to around 3500rpms (this is on cold motor, its NOT idling so I CANT get it up to temp really, well I could but its a PITA) black plumes come out, I'm getting a lot of fire/excessive popping. The fire is bluish white down low when its doing it also...Now above approximatly 3500-4500rpms to redline its fine and screams like I remember the old engine doing still with fire but orange now (old engine used to hold a reddish orange flame out the tailpipe at WOT from what I've been told many times). It feels responsive up high too but not quite as much as it should but I may be wrong. As soon as it gets below this certain rpm though its just like "I hate you". It looeses almost all responsiveness in the way that like I floor it and it will still downrev for a few moments and then build back up, its unbelievabley rich acting/smelling (weedwhacker/go-kartish), it sounds like a harley becuases its missing on at least one cyl but it seems more like 2-3 but again up high its NOT missing and NOT acting odd at all.

I've tried adjusting dist timing, I pulled the distributor bolts out so instead of having the slots range I have like a lot more, with it MAX advanced it will crank over and run, with it in slot-range it turns over like 1rpm/min and pops occasionally. With it MAX retarded and a spark plug rotated to make it even more retarded (essentially i think it makes it like 10 more degrees advanced than the max advance I mentioned a moment ago), it will go up to like 3500rpm idle and hold steady briefly (3-5seconds) then it'll started losing momentum and still stall out.

I checked my ignition timing via pulling the oil pump. Its okay but I don't think it can be timing, its fine up high and I with all that distributor adjusting space you would think somewhere along those lines it would be okay.

I pulled the injecotrs and then checked the resistance on them, I forgot to mark the cylinders they came from though.. I got 13 on three and 14 on one of them, spec is apprantly 10-15 so i guess its fine? I also connected them to my battery to see if the solenoids clicked and to watch them. All of the silver-dots on the end moved, i did notice on one of them that dot was deeper inside than the others (others were flush with the black housing at rest, this is inside and never moves out enough to even be flush?)..

Before I pulled them I did indivudually check the injector (one plugged at a time) and coil relation. Basically grounding the coil out to the frame, leaving one injector hooked up and then rotating the rotor with the CAS hooked up. They were firing 180off which I believe would be correct.

No ECU Codes are present either, I checked by battling the engine for like 2minutes and then checking Mode-III without turning the vehicle off.

Since I'm not getting codes I doubt its a MAF or TPS problem, I've had MAF problems, I believe it has about a 3krpm rev-limiter and goes to a limp mode right? Well mine acted like that both times at least lol.. Vacuum leak = Lean not rich and not self-correcting at high rpm for sure, unmetered air would increase AFRs not decrease.

Everything I think of would be a problem enabling low rpm but not high rpm drivability, or is a lean condition problem not rich. I've never really dealt with an isssue close to this and I really dont have the money to go into needle/haystack mode right now but I do have enough money to fix what I need to. I'm building a CA18DET for next spring and I can't see myself spending like $600 on useless crap that I'll only use for a few months (i.e. new injectors, 02 sensor, maf, tps, the works and hoping one of those fixes it).

Summary, Thanks and Last Minute Info:I know thats kind of long, but I figured the more details the better the help. I'll admit my timing might be slightly off and thats why it runs better out of the slots range, but its at its best running timing right now really, even if it is out all getting it "in" will do is put it where its in the slot area. So SOMEONE PLEASE HELP, I've been down a car for 7months, bought a second car and it died the second day (was sold a time bomb). I seriously miss leaving on my own free will, especially since I live in the sticks and I cant walk anywhere. Its almost running, 100% by myself. But we all need a little help sometimes. I hope I can find it on here.

Oh and while I'm thinking about it, the gas was premium gas bought in Dec of 06, lol. That shoudn't be a problem though right? Again if octane is an issue I should be laying down hard detonating on high rpm and its fine. I had a some gas from the fuel rail in a can when i pulled everything and a match ignited it rather well hehe so its not watered to the point of no-ignition.---- Thank you and apoligies for length.
Modified by KASilvia90 at 9:42 PM 7/11/2007

[KASilvia90]

No one has any ideas?

[thomasjamal]

That's tough. It really sounds to me like you have more significant problems than timing issues and I don't think injectors are your problem.

A common problem to check if you haven't is the throttle body/throttle plate. It probably needs to be cleaned and that may help some.

I'm not sure what else to tell you but at least here's a free bump.

[GTR PrYdE]

Dude, try unplugging your MAF. See if it at least holds an idle.

I removed my intake and removed my emissions(track car) and it wouldnt idle when put back together.

I could rev the car all I wanted, but if I let off the gas it would drop down and die.

Maf was fine before hand- but I unplugged it and it held an idle fine- with the 3k rev limit of course.

I guess it got dirty while it was disassembled.

Takes 2 seconds give it a try