beyond confused

[jdmser]

I've had the motor running for a few weeks now and have been trying to get a good idle out of it. It was idling cold without problems but, when it gets hot it starts to stumble like its running out of gas and eventually dies. I have checked for boost leaks and fixed what I found, cleaned the maf and plug off, replaced the fuel filter, went to a warmer heat range of plug, hooked the fuel pump up to the battery with a relay, and cleaned the throttle body. After replacing the fuel filter and cleaning the trottle body today it died after idling for a while and wouldn't restart. I have checked continuety through out the entire ignition system. I did notice that the alternator was only charging at 13.5v and wasn't very responsive when I increase the rpm. Now heres where it gets weird, I pulled the inline fuse to the fuel pump and put a spark checker(spark plug wire looking thing with a noid light in the middle) on the second coil. I taped in up so it wouldn't fall off and started to crank. The damb thing fired right up. It had been sitting for a while now and cooled off some but, I didn't have the idle control hose, bov vaccum, or cross over pipe on. One thing I did notice is that after I cleaned the throttle body it ran real nice on the carb cleaner. It has been sitting for little over a year. I added about 4 gallons to the quater tank I had maybe that wasn't enough? Maybe I didn't clean the throttle body well enough? I'm honestly out of ideas. Any thoughts?

[91240sx rb20det]

i think your supposed to run colder plugs on a turbo car. also was there gas in the tank when it was sitting for a year if so the gas will go bad. try draining your tank filling it with high octane and use colder plugs and see what happens.

[jdmser]

It had ngk 3330 when I went to emission test. After it failed I went back to the factory heat range. I've heard that they put a hotter plug in at the factory because it runs better when the car is only being driven very short distances. As for the gas, that's going to be one of my next steps.

[jdmser]

Anybody got ideas about why it runs with the fuel pump fuse out and no fuel pressure?

[jdmser]

I think I've found my problem. This video Click here to watch DCP-1264 sucks but, I had to turn the lights down some so you could see the spark. At any rate, the spark seems really weak to me and it's a brand new plug. Could a bad ignitor cause this?

[Carl H]

what do the afrs look like when it does this?

[jdmser]

As soon as it starts to stumble the afrs go rich then leans way out for a little while and then dies. Sometimes if I blip the throttle it will stablize and I get good afrs but, when after I cleaned the throttle and it wouldn't restart I pulled all the plugs and they are fouled real bad. I'm thinking that the spark is just too weak to ignite a full shot from the injectors but, with the fuel pump fuse out it's just burning the vapors from it being flooded before. When it run's with the fuel pump fuse out I was seeing 10.5. I'm going to unplug power to the injector with the fuel on just to make sure it's not an injector that hung open.

[digzsublime]

Spark looks fine. It's not supposed to light up the room. The engine will start after you pull the fuel pump fuse. It will run (especially at idle) on the pressurized fuel that is left in the lines for a minute. But, it will eventually run all of that out and die.

After sitting for so long, it is possible that the idle air conrtol valve is sticking. Also possible that as the engine heats up, ignitor fails causing no spark until it cools down for a minute. That one may be a long shot. But, if your testing the spark immediately after it dies and it's still has spark, then that is probably not the case.

Hopefully Carl H is going to have better input. But, I would put everything back together and go drive the car if possible. Don't take it out and beat on it. Just go drive it around normally and see if it runs o.k. whunder boost and all. That way you can see if there are any other drivability issues. Might not hurt to burn out that old gas either.

Possibly Idle Air Control Valve sticking, and not letting enough air in once engine is warmed up?? Might explain the fouled plugs. Also, I assume that you've checked base timing and it's good. WIsh I could be more help. Hope it all works out for ya.

[FAST-DATSUN]

the problem is problley in the IAC valve or the wiring to it....check to see if the plug has 12v KOMO

[jdmser]

One thing I haven't mentioned in this thread is that I keep throughing a code 21. Does the ecu through this code if the plugs get fouled or is it just if you have a bad coil or ignitor? Anyway, I have cleaned the aacv, throdle body, replaced the plugs, and put it back together. It idled for about 30-45 seconds at 10.5 afr and then died.

[Yellow4g63]

Did u try unpluging the Air Flow meter and see if it idles on it's own?

[Yellow4g63]

never mind

11 Crankshaft position sensor12 MAF sensor circuit13 Coolent temperature circuit14 Vehicle speed sensor circuit21 Ignition circuit31 ECU (ouch!) 34 Knock sensor 43 Throttle position circuit45 Injector leak51 Ignition circuit 54 Auto signal to ECU55 All OK

[jdmser]

It has to be something I did recently or something that failed recently. Last July I blew the turbo at the track and since then it's been in the garage getting upgrade. Since the last time it ran well I have add emanage, Q45 maf, sard 660, new intercooler and piping, ported the head, tomie cams and springs. The only thing that would effect the ignition circuit would be the ignition harness of the emanage. I may just unwire it. The only other two things causing that code would be the coils or the ignitor. I've check and have good continuity from the coils to the ecu.

[digzsublime]

Next time would help out alot if you mentioned that you added all those things. The more info you give, the easier it is to figure out the problem.

Hope you get it going man. Sounds like it's gonna haul when you get it running properly.

[jdmser]

Yeah, sometimes I forget not everybody lurks as hardcore as I do. Anyway, I have gone through the ignition system with a fine tooth comb and the only thing I can come up with is the code 21 is from it misfiring. I put new plugs in and tried to start it again but, no good. I pulled the plugs out and they wore wet but, I tried putting a lighter to them and they wouldn't burn? I would have thought that the drop of gas on the end of the electrode would have lit.

[digzsublime]

Won't burn if it's not gas. Quick question. When this car sat for a year, was the gas cap on it?? Yeah I know it's a dumb question. Just checking cuz it if wasn't, you may have condensation in your gas tank.

I bought a car like that once. Guy said it wouldn't start. It had been sitting for 2 years with no gas cap on it. The gas door was closed so he never thought of it. I doubt that is your problem. Just something I threw out there.

If it makes you feel any better, I finished prepping my car for paint yesterday. While I was having a well earned smoke, I noticed that my overflow tank had a nasty ring of something inside it. I imeadiately thought "You gotta be f'ing kidding!" took off the radiator cap and yup, had a little oil in the coolant. Not cool.

Not trying to thread jack. just thought it might make you feel a little better. G/L Let us know if you igure anything out. I'm curious to see what is causing your problem.

[jdmser]

The oil in the coolant sucks, hope it's just a head gasket. I acctually suck the gas tank and fuel lines dry with a vaccum hooked to a gas can tooked to a siphon pump. No, not the safest thing to do but, it worked. I just finished pulling the injectors and they look clean enough but, I,m sending them off anyway. One thing I did notice when it was running was that the emanage never showed the injector duty cycle higher than 6%. I didn't think that was right because of the afrs at the time. Tomorrow I'll be pulling the radiator and timing cover and checking cam timimg. If the injector turn out good and cam timing is on and it still doesn't start I'm unhooking the emanage.

[jdmser]

Found an interesting piece of my puzzle today. I picked my injectors up from getting cleaned and flow tested and found out that my Sard 660cc injector are really my Sard 730cc injector. Could be why when I put the fuel pump on the relay that the plugs started to wet foul.

[Carl H]

thats a good 90cc diffrence and could definately lead to flooding out...

[jdmser]

Did the injector correction on the emanage and it fired right up. I turned the fan control off and let it start warming up and it finally through a code I could work with, etc. So that's why it would idle real rich at first and when it warmed up enough. It would fall on it's face because of the ect telling the ecu the wrong temp. I had my fans set at 160*, I guess that wasn't hot enough to get it out of range. It now idle between 12.5 and 13 afr. I also got 14in/hg at 15* of timing when idling at 1000rpms. I still have a miss during idle but, it doesn't seem to be the same cylinder every time. I'm going to try gapping the plugs down some and see what happens.