engine stall while driving... intermitant valve slaping after warm

[cellaboy]

hello all,i just bought 92 Maxima SE M/T with 112k on her. on the test drive he car had good power but ran a little rough (didn't effect performance). when the drive was over i left the engine running and that is when i heard the slapping. it comes in for about thirty seconds and stops. if you rev the engine it goes away. but sometimes returns a few seconds back in idle. what could this be?

also, the other day i was driving about 55mph in 3rd gear and the engine stalled. i was confused/surprised so i pulled over pressed the clutch, turned the key and she started right up.are these problems related? what could they be?

thanxJP

[xcanox]

As far as the valve slapping goes. It's not really valve slapping at all. Turns out it's the VTC. It advances the timing at the wrong time (ie. at idle). This is why when you hit the gas the sound goes away. A quick fix would be to ground the VTC shutting it off. This will stop that sound. I do recommend replacing it but it is a big (and pricy) job.

As for the car stalling out, I'm still working on that with my Max. I suspect aa sensor issue, but because the problem is intermintent it's been a P.I.T.A. to Diag. I'll Post whn I figure it out though. Good luck.

[300ZXbyCP]

Regarding the VTC, if the VTC is cycling max advance to max retard at idle, that is a problem. I wouldn't "Ground out" the VTC sensor as this will cause an erratic or rough idle. Best bet is to fix the problem.

With the second condition of stall at 55 and restarts ok, this points to electrical issues. Generally, there are only two sensor / control outputs that will shut the engine down:* Crank Angle Sensor (CAS)* Ignition Amplifier

Bad electrical connections or poor grounds will cause the engine to shut down and give false readings to the computer controlling the VTC. If it were a bad component, it usually just fails. Test this by separating the connectors and look for that green-white connection killer - corrosion. If there, clean with electrical connection cleaner, gently brush with a brass brush, repeat steps till clean then use connection paste to reassemble (or buy a new harness and sensor). To test the ground resistance of any component, use an ohm meter between the component and the negative post of the battery, reading should be as close to 0 ohms as possible. To improve ground resistance, clean physical connections or add additional ground wires.

Hope this helps.

[xcanox]

I Definitly agree with 300ZXbyCP. Fixing the VTC would be the better way to go. There is a service bulliten about this problem. Nissan actually recommends repairing the part instead of replacing it. Here is a pdf from nissan about the issue, it also shows you (or a mechanic) how to properly repair the part. Even if you bring it to a dealer, I recommend showing them this PDF so they fix it the right way. We all know how some dealers can be.

http://maxima.theowensfamily.com/tsb/NTB95-022.pdf

Hope this is helpful.