Built Gtr Problems

[ShadowGTR]

I have a fairly new built engine approx 7000k and everything has been fairly good. last couple of weeks it has been harder to start at hotter temp(above 60), it starts but takes quite a few rotations, besides that, no prob.

the other day i drove to my brothers place and it was fine, when I left there my a/f ratio gauge went ballistic saying it was leaning out (gauge only goes to 20:1 and it was sitting on that) but everything else pointed towards it running rich ie. injector duty was up, exhaust temp was down 100 degrees more than usual and as soon as there was any sort or load there was visible black smoke.

At idle the a/f ratio was back to normal (14) but the slightest touch of the pedal and the gauge would go ballistic again.

on the way home I overtook a car and when boost hit around 1 bar it surged badly and sounded like a silenced gun going off and the knock reading hit 78.

The welsh plug at the back of the head blew out but luckily I was very close to home so it was parked straight away, so I know some of what needs to be done, but I don't think the it simply comes down to a faulty plug, is there anything that could cause excess pressure in the coolant channels?

I had a look at my manual and some of the problems it was having can be attributed to faulty sensors, but all the standard readings were fine. and my gauges run on their own sensors.

reason I'm asking you guys is because my mechanic is on holidays till the end of the month, so I thought someone here will probably have some light to shed.

the car is heavily modified running a very conservative tune at the moment.

[The Dan]

Check AFM's and O2 Sensors. Also check for vac/boost leaks

The ex temps are cooler because more fuel is being injected. The injector duty is up because the ECU thinks it needs more.

What a/f ratio gauge is it? Narrow band? or do you have a 4 or 5 wire wide band fitted?

[Keeper]

Sounds silly but did you check your fuel pressure?

[STATUS]

whena wide band starts to die it reverts to 20:1 and up to eliminate the chance of it going un noticed

[ShadowGTR]

afm and o2 sensors are brand new. doesn't mean to say they aren't possibly faulty.

I have a fuel pressure gauge as well with a big adjustable reg, everything was normal there.

its a prosport wide band a/f gauge, 5 wire using a bosch sensor. http://prosportgauges.com/wideband-60mm-ai...mber/White.aspx

it had to goto epa for an inspection with boost controller etc removed, so the vacuum/boost line may have come loose on re-installation, would a vacuum leak cause the comp to go nuts that bad? It sounds like the most likely cause if a line simply came off, as the problems literally hit instantly, stopped the car, started it 5 mins later and it was stuffed.

The a/f meter an sensor are both brand new, and they are on a seperate loom to everything else so its reading shouldn't affect the way the computer behaves. if it was just a faulty sensor I'd be over the moon.

Edited July 11, 2010 by ShadowGTR

[Moodles2]

Do you know if the new O2 sensors were Titania-type (not Zirconia-type)?

[ShadowGTR]

not sure on the type of the o2 sensors. they are the bosch replacements for standard.

the exhaust temp has been fairly high under constant load at times (900c) could I have burnt them out already?

[Moodles2]

not sure on the type of the o2 sensors. they are the bosch replacements for standard.

the exhaust temp has been fairly high under constant load at times (900c) could I have burnt them out already?

It's just if you got Zirconia-based sensors it might explain the gremlin as the 2 types are electrically different to each other, and the R32 GTR ECU expects a pair of Titania-based sensors

[ShadowGTR]

The package has been running for a few k's now, and its running a power fc. if there was a problem with parts intermingling it should have shown itself by now, but its worth checking out.