Thread: Update on my red car (still need a little advice)

Depending on how many coils have bad firing the timing could be off, but usually its in the high rpms (on all cylinders) where you would notice the timing being off. But the mis shifting or harsh shifting could knock the timing out a bit if you think about it. But then again I figure that if it was knocked out that much, he wouldn't have compression because the valves would most likely be bent

AEM EMS can run a MAF, but 99% of installations run MAP. I'm sure his is no exception.

BenFenner: The direct ignition is stock Maxima coils. They have 3 leads, +12V from the ignition switch, ground from the chassis, and then a signal coming off the AEM. The coil packs look fine, I've blown coils early on because of a short, the result would be a big bulge in the plastic casing. I can almost eliminate the coil packs themselves.

HKS, The standalone is completely independent in every way to the rest of the wiring. I cal literally disconnect every sensor and pull the EMS in about 10 minutes.

squabzter: I'm getting a feeling you may be right, about the cam sensor, actually, I'm hoping it's wiring or a cam sensor, I'm getting a worse feeling about the timing. It wouldn't be an individual coil, the V6 can run on as little as 3 cylinders, I've seen it. All 6 plugs/coils are having erratic spark patterns.

Coheed: answer above.

Phatsomax: thanks for joining to help. I'm starting to get the feeling you're right, but I'm hoping you're wrong. If I jumped the timing chain, dropping this engine is nearly impossible. It's wedged in there like canned tuna.

Still, if I were off, a little, wouldn't I still be able to start? I've been off a tooth before on my first SR20, the car still ran decent. And if I were off a lot, I'd imagine I'd have compression problems or bent valves.

I imagine the UDP is like the chain tensioner, and I don't know the CKPS/CPS means. The AEM still utilizes the VTCS solenoids so I still have a variable timing map built in. Also, I'm using a MAP system. The MAP is a 1bar GM MAP sensor.

Topdog: The Portal

Nismo87: Can't use a timing light without the engine turning over, even so, I'm not sure if the induction sensor would pick up the signal from a direct coil.

squabzter: If the timing was off before this incident, I didn't notice a thing, the engine makes ~300hp/tq at the crank. My last dyno was 260/260 at the wheels. Never mis-shifted or over-revved. I would know, because that's how my VVL bit the dust. For the record, my compression was around 200psi in every cylinder (all plugs out, plenum removed, 10 cranks)



I'm praying a rewire will solve the issue. If not, I'll remove the valve covers to see how the cam pick-ups/sensors are doing. Worst case, the engine has to come down and I have to break into the timing cover.

If that happens, I may just do a cam swap while I'm at it. I never, ever, ever, ever, ever, want to have to drop this engine. The exhaust is routed in such a way that there are no flanges. The headers are welded together at the y-pipe merge. Removing the engine requires me to cut the exhaust.

Phatso's car ran, although pretty lopey sounding, with his mech. timing off. Cps is crank position sensor, think ckps is knock?

The VQ as well as the SR are non-interference motors, IIRC. I've been off at least 34 degrees of mechanical timing and didn't bend any valves. Car sounded like a v8 and ran like a two stroke lawnmower.

Good luck!

Actually.
CKPS=Crank position sensor
CPS=Cam position Sensor


I could be wrong! LOL

if the engine came out of a maxima which i think it did, you may want to get the vin from the block if you can and take it to a dealer, they had a recall on those to replace the crank, and cam position sensors, so i would say that could be a definate issue.

The SR is an interefence engine, and so is the VG so I would assume that the VQ is as well.

SR20 is an interference motor. At least that's what I've been lead to believe for the past 6 years.

Yes, they're both interference motors. I've bent valves in the past.

I'm still thinking that if I were off a few degrees I'd still run, and if I was really off, my engine would be toast.

My VQ doesn't have a crank position sensor. I don't know if any VQ does. RPMs and timing are determined at the exhaust cam, IIRC. There's a cam position sensor on the 1-3-5 exhaust cam, and there's a cam position sensor on the 2-4-6 exhaust cam.

When I first installed the ECU, I was required, by the guy who programmed it, to modify the 2-4-6 exhaust cam where the sensor picks up the cam position. I was to leave a single notch in the cam at a specific angle (very high tolerances). It is my guess that the 1-3-5 cam (rear of engine bay) sends cam angle data back the ECU, and the 2-4-6 cam sends RPM data back to the ECU (acting like a crank position sensor). If that's the case than maybe the rear sensor is bad or has bad wiring.\

NSMO240: There was a recall on the sensors? Hmmm, I may give them a call. It was an early VQ35 (2002) Maxima.

That's wierd. I've been told that they're non-interference motors, which made sense when my timing was WAY off, and I didn't bend a single valve... At over 30 degrees of mechanical timing being off, you almost HAVE to break something!

I stand corrected. Good luck at any rate