infiniti q45 engine problem

[infinitq45]

Well my worst fear came true today. My unstoppable, unbreakable q45 broke down!!!

I drive a 1990 infinti q45, with 228,000 miles on it.

It was working wonderful just yesterday and today i turn it on, warm it up, hit the gas and then all of a suden i hear a crack, boom, crack, but the engine still runs. The problem is that when i hit the gas i can go to about 2,000 rpm but nothing more than that or it stalls. If i'm in neutral i can go to 7,000 rpm but then i'm not engaged in a gear.

If any body has any clue to what happen, I would be very grateful.

Thanks,Paul

[landtodd]

Get thee to a Consult! Speaking from memory, it sounds as though you may be in limp-home mode. Did the ECU light the check-engine light? You're limited to about 2K rpm when the ECU is in limp-home mode, and the fuel injection is similtaneous rather than sequential.

[maxnix]

If you haven't done this yet, don't even think about starting the engine!

[greg_atlanta]

If the timing chain slipped I'd think the engine wouldn't run at all???

Give us an idea of what major work has been done and how long ago. Sounds more like transmission problem to me, but I didn't know transmissions made noise when they broke.

But congrats on 228K miles!! I'm up to about 181K on my '92 Q and getting a little neurotic, but I keep charging on!!

[DAEDALUS]

I would bet dollars to donuts that the driver's side guide is long gone and in the oil pan. If the chain had slipped (can they?) I think the car could run but not to 7000RPM.Paul, is the noise constant, or did it go off and then stop? Does the car run smoothly in neutral? We could guess away, but without an error code this might be a rare case in which the Consult is the best answer as Todd suggested. Ask a Nissan or Infiniti dealer for diagnosis. They'll probably charge you an hour's labor, but once you know what's wrong, we might be able to help a lot more if you're the DIY type. Don't buy any parts from your local dealer!

[infinitq45]

Thanks, to all those who helped but somehows, magically, my car is working normally again, i went to turn it on and everything with the car was working just fine. Thanks a lot for the help, DAEDALUS, greg_atlanta, maxnix, and landtodd!

[DAEDALUS]

That's great news. In my experience strange noises don't just happen for no reason; something causes them, though you may not find out what for a while. Hopefully it's nothing major.Please use the red search button and look up "chain guides". Lots of info you need to know if you haven't yet replaced yours.

[landtodd]

You ought to track that down if you're interested in the car's continued service. The "healing" suggests to me that it's an electrical problem. Even if the ECU set a code, if it doesn't see the problem for (I think Dennis said) 6 starts (?), it erases it from memory.

The guides haven't been replaced ??????

Since you mentioned a bang (maybe backfire?) let me echo the advice -- stop driving until you figure it out. Your motor may be in peril. If it was a guide breaking that you heard, even if the parts of the chain guide made it through the motor, where did they end up? The oil pan, where they've been known to clog the oil intake.

Keep us posted!

[Chally]

Had the same type of problem in a Nissan here once.It turned out to be the Torque Convertor siezing up & it would stall the engine when cold.

The guy had to warm the engine, & obviously the convertor, for about 10 minutes before he could drive away.