3000GT/Stealth International Message Center - View Single Post - Lean Misfires at 2700-2800 rpm

G3000 · 04-27-2008, 05:49 PM

I have been watching this and every other forum regarding this problem since I replaced my engine with a used Japan spec. engine 11 months ago. I found my problem yesterday and needless to say am very happy. The problem was bad spark plug wires even though they had been replaced new (Autozone or Advanced Auto junk) about 15000 miles ago. I found this by replacing the front three newer wires with the older ones that came with the used Japan engine and noticed a very slight improvement so I removed the plenum and replaced the back three wires with the remaining three older wires. The problem completely dissapeared.

The newer wires looked fine and had low miles on them so I tried everything else first and I mean everything, such as CAS, TPS, injectors (after cleaning and re-cleaning two different times), engine temp sensor, etc. from other engine and new spark plugs (twice), new high volume fuel pump, pump relay bypass and probably many other things I am forgetting.

Also my old ECU failed (fire and smoke) so I replaced it with a new $900.00 ECU when the engine went in 11 months ago. In case you are wondering, yes I did check the capactiors about 8 months prior to the engine replacement but I suppose in the 3 months the car sat before the engine replacement they failed.

The bottom line for my car was that even though it acted like a fuel problem it was ignition issues cause by bad spark plug wires. My plugs looked white, like a lean condition or lack of fuel but don't be tricked as it may not be the case. No doubt the ECU was making all kinds of incorrect adjustments caused by the faulty spark plug wires.

It seems that no matter how new your spark plug wires are you should revisit the wires and replace them, particularly if you have tried everything else. Make sure you replace all six wires as murphay's law suggests more than one will be bad and some will be in the rear of the engine as was my case.

Hope this post helps someone else as this problem is the worst I have ever seen in any cars I have owned or worked on.

04-27-2008, 05:49 PM	#726 (permalink)
G3000 Forum Member Join Date: Feb 2005 Trader Rating: (0)	Re: Lean Misfires at 2700-2800 rpm I have been watching this and every other forum regarding this problem since I replaced my engine with a used Japan spec. engine 11 months ago. I found my problem yesterday and needless to say am very happy. The problem was bad spark plug wires even though they had been replaced new (Autozone or Advanced Auto junk) about 15000 miles ago. I found this by replacing the front three newer wires with the older ones that came with the used Japan engine and noticed a very slight improvement so I removed the plenum and replaced the back three wires with the remaining three older wires. The problem completely dissapeared. The newer wires looked fine and had low miles on them so I tried everything else first and I mean everything, such as CAS, TPS, injectors (after cleaning and re-cleaning two different times), engine temp sensor, etc. from other engine and new spark plugs (twice), new high volume fuel pump, pump relay bypass and probably many other things I am forgetting. Also my old ECU failed (fire and smoke) so I replaced it with a new $900.00 ECU when the engine went in 11 months ago. In case you are wondering, yes I did check the capactiors about 8 months prior to the engine replacement but I suppose in the 3 months the car sat before the engine replacement they failed. The bottom line for my car was that even though it acted like a fuel problem it was ignition issues cause by bad spark plug wires. My plugs looked white, like a lean condition or lack of fuel but don't be tricked as it may not be the case. No doubt the ECU was making all kinds of incorrect adjustments caused by the faulty spark plug wires. It seems that no matter how new your spark plug wires are you should revisit the wires and replace them, particularly if you have tried everything else. Make sure you replace all six wires as murphay's law suggests more than one will be bad and some will be in the rear of the engine as was my case. Hope this post helps someone else as this problem is the worst I have ever seen in any cars I have owned or worked on.