95 g20 - wont rev - idles fine

[elvis240sx]

OK, I have already searched and came up with nothing. The car is a 93 Infiniti g]G20, but last winter I swapped in an engine from a 95 G20T. I used the newer G20T wiring harness and ECU. The car ran great until about April. Since winter was over, I just put the car away and got the 240 out.

The problem was, the car would idle fine, but suddenly had no power. Literally, it would not get out of it's own way. At about 4500 to 5K RPMs it would start to pull harder and seemed to run right. I didn't bother fixing the problem until now, as i am trying to get the car ready for winter.

I replaced the plugs, wires, cap, rotor, fuel filter, air filter. It still did the same thing. I noticed, however, that the #2 spark plug looked perfectly clean, but the other three looked like a nice burn. I checked for spark, and they all had spark. this led me to think a bad fuel injector. I had four extra injectors lying around, so I pulled the plenum off and swapped out the #2 injector. after putting it back together, I started up the car and it ran great! I ripped up the road a couple of times and everything was fine.

I then started the car back up after a few minutes and it started hard, but then seemed to idle fine. When I pulled out of the garage, the car fell flat on its face. If you just open the throttle normally, or pull it open quickly, you can hear and feel the engine just bog down. The engine will die if you hold it open, it just dies out very quickly. It sounds like the car is running out of air almost, like choking. Now heres the weird part, if you crack the throttle really slow it will rev up all the way to redline. If you rev it slowly up to the upper RPMs then whack it open all the way quickly, it still bogs down but not nearly as much.

What iI determined:-all cylinders getting spark-charging at 14volts-fuel pressure 40psi at idle, climbs to 50psi when open throttle-unhooked MAFs, car runs the same or slightly worse-took airbox off to test for air restriction, didn't help-compression all about 170psi except cylinder #2 is about 155-160psi-sprayed carb cleaner all over intake/hoses, cannot find intake leak. -when putting head over engine it sounds like air blowing (intake leak) but could also be electric fans or p/s belt? ?

Any help would be appreciated. I am wondering if this sounds like an intake leak? Or would it be more of a sensor / wiring problem. It just seems weird that if you open the throttle really slowly, it can rev way up. If you whack the throttle quick, it just falls right on it's face. It seems like maybe the ECU can't adjust fuel or timing quickly enough to handle the increased air / load? I dunno. Any help is appreciated

[elvis240sx]

one more thing,when i spray carb cleaner or starting fluid into the throttle body the car bogs down the same way as if whacking open the throttle. so it seems like whenever the car gets the extra fuel it dies out. i am thinking it must be an ignition problem or an air leak. maybe i will just pull the plenum again and look for leaks or disconnected / broken hoses. i wish i had a smoke machine to plumb into the throttle body to check leaks.

any ideas? lol

[Jesda]

Bump.

[elvis240sx]

i hooked up a vacuum gage and it was about 18 at idle, and went to zero when you whacked open the throttle. i also found the metal tube to the bpt valve plugged, causing the egr to not work properly. i pulled this tube off of the intake manifold and reamed it out. doesn't help any. anyone have ideas? i got an "adjustable spark tester" but it says the spark on a normal car should be able to jump 10mm. i opened it up 10mm and the g20 cant jump it. the most it can do is about 4mm. is my ignition system weak? spark isn't strong enough to ignite when under load? i am also wondering if my crank angle sensor or cam sensor is bad? i cant seem to find much information on either of them. or even if they exist lol any help is appreciated. i want to be able to drive the G!!

[Dcharn1]

did you ck the knock sensor?

[elvis240sx]

here is the latest news on the g20

i marked the location of the distributor, then loosened up the screws and started turning it. with the distributor turned all of the way to the right (towards firewall) the idle smoothes way out and has no blips or skips to it. you can also whack the throttle and it will respond fine and rev really easily and quickly, like before the problem started. i would say now it is 95% better.

so, what does this mean? by turning the distributor to the right, did i advance or retard timing? i am thinking maybe the knock sensor is bad and telling the ecu to retard or advance timing ? or the crankshaft position sensor is bad ? i am having trouble finding testing procedures for each of these sensors. any help is appreciated.

i dont think the timing chain jumped a tooth to get off of timing, because some major engine failure would occur if that happened, right? lol

[Q451990]

I don't have any specific G20 experience, but I don't think a bad knock sensor should have that much impact on your engine's performance. Typically you'll notice some difference - but nothing like what you describe.

I wish I could help more...

Heath

[Q45tech]

Set the basic ignition advance correctly with a timing light, then use a Consult to diagnose.

95 engines are weaker than the 90-93 from emission cams and head ports.

[elvis240sx]

ok, i put the distributor back to where it was and warmed up the engine. i hooked up a timing light to check timing. when the engine coughs or sputters, the timing light stops flashing. the same as if you whack the throttle open fast, the timing light just goes out until you let go, then it comes back and the engine continues to run. does this mean that under load the ignition spark just cuts out and stops working? i hooked the inductive probe up to each wire individually just to see if the same thing happened under these conditions, and it does.

when i rotate the distributor towards the firewall (idle is much smoother, can whack throttle open and engine does not bog or die out) and start it, the timing light never stops working. even if you whack the throttle open quickly, the timing light just speeds up with the spark. is it maybe a bad spot in the distribor ?

[bullittandy]

I'm not certain I understand the problem, or if this is even possible but it sounds like your distributor is inserted "one tooth off." Was the distributor moved and/or removed?

If this engine is like an Amercian V8 then find TDC on #1 and reinsert the distributor with the rotor pointing to the #1 plug wire.

I hope this helps.