john93se

Hi all,

I've spent a little time looking in the forum this morning, I'll admit only the first few pages back. I'm trying to figure out what's going on with my car, so I'll try to explain this best I can:

Car was misfiring, seemed like cylinder (#6?) up closest to drivers side on back bank. Took it to my local mech who thought that was the case too, had a parts engine and swapped that, the camshaft position sensor, and I think the crankshaft pos sens. After he changed the coil he drove it a bit and said that the car completely died on him randomly. Sometimes it would misfire, sometimes not. After a few drives it was extremely inconsistent. He was on the highway and it just turned off and he had to pull the key all the way back and then crank it again as it wouldn't work when he just tried to crank the ignition again without putting the key back beyond acc mode. He made no progress as he put the other parts in.

He's since put all my original parts back in but is stumped. Could it be the ECU, knowing that the car must be shutdown electrically before being turned back on? I'm really unsure of what's causing this and any help would be appreciated greatly.

Greeny

iTrader: (43)

Well first off....Your mechanic is not a mechanic...He is a parts changer.
Real mechanics diagnose the problem then fix the part that is bad...Not just throw parts at it, hoping he can hit the bullseye.Thats a good way for him to rack up some
nice labor charges on you.....

As for your problem...check the ecu for any stored codes..if there is none then I would check out all the connections to every sensor there is on the car for corrosion/bad connection. check all grounding points in the engine bay.
That will eliminate a bad connection being the problem...

john93se

I must admit I left out a few points then and that is my fault, I was typing frantically. He had the computer hooked up for codes. The only thing it threw was the KS apparently. He was looking for grounding issues and couldn't see anything. He thought it might be that something was heating up and dying, but then he couldn't attribute why turning it off and back on would do anything. As for checking every single connection in the car, well I can't say that he did that. I don't know when I'm going to have that kind of time. But it hasn't acted up in my 30 minute drive to work. I don't plan on paying him, he hasn't fixed anything. I'd consider paying if he could even diagnose the problem but... oh well. I'm not sure how common it is for a snap-on reader to go bad or just not print codes, but I'm at my wits end. I'll be checking connections when I get time. Hopefully I can get some lights and look it over tonight.

edit: by the way, I can find WHAT the codes mean in stickies or whatnot, but I could never quite find WHERE the **** is to output the ecu codes. Is it hidden somewhere unlike the very obvious **** right on the side of the 4th gens?

Greeny

iTrader: (43)

http://www1.autozone.com/servlet/UiB...3d801f5017.jsp

http://www1.autozone.com/servlet/UiB...3d801f5cfe.jsp

john93se

I hate my car sometimes, I must have looked right at the damn thing, because I know I checked on both sides... Anyway, I appreciate the diagnostic location. I don't think running codes on the dash is going to reveal anything beyond the snap-on but I guess there's always room for suprises.

Greeny

iTrader: (43)

Oh by the way, if you still just get a knock sensor code,That part being bad would not cause the problems you are having....

vansskaterfreek

iTrader: (14)

did you try resetting everythign in the car??? take negative off of battery for a second and put back on, it resets everythign from loss of power, it just might need a reset

Wiking

Sounds like ign sw ACC to ECU drops off. Start from charge voltage checks at batt, ECU. Clean ECU connectors.

At that crucial moment whan fault is ON, u can check for spark, fuel hose stiffness =pressure"ok", listen to injector clic [rotate cam sensor]. If spark and/or inj click, ECU gets voltage supply and is about alive.

vansskaterfreek

iTrader: (14)

i searched your cardomain wiking and couldnt find a diagram of a bad connection with ECU, what i mean is the pins getting worn down maybe you can direct him to that please.

Cliff Clavin

iTrader: (11)

did your mechanic swap in a new coil pack or just swap around your current ones?

There are several threads going back years ago about stalling issues with VE engines. Most of the problems center around coil packs. My car died intermittently, especially on hard acceleration. It was one of my rear coil packs. Mine did not show any codes for the problem, even minutes after it happened.

There are only so many possibilities, too. Basically, various electronic components and the connections to the sensors would be my first method of attack. You tried the Cam Sensor, but did you try a different throttle position sensor? MAF sensor? Ignition module?

I am assuming your mechanic checked the impedence on your injectors, too? I don't think this would cause the car to shut down, though.

It is pretty rare to see ECUs die on these cars, unless they have seen some kind of water/liquid. Also, if you don't want to spend a lot of money seeing if it is the ECU, browse through junkyards for VE engine cars. You didn't say if you have a 5-speed or AT, but an AT ECU will work in a 5-speed car, but you will lose your variable intake. I tried one in mine to see if that was the problem, too.

Good luck

john93se

I'm a little confused by what you mean. Start from charge voltage checks at batt, ECU? Should I try checking those connections for corrosion? I'll try the battery reset but what would cause the car to misfire in the first place if there was no problem? I wouldn't think that my car would just mess up randomly and wait to be reset, but then again I can't say I know much about my car.

Yes, it is a 5spd; sorry for not making that distinction

Red89maxima

Are the 89's the same ??? For some reason I can't access this site to find out.

thajones

iTrader: (4)

For askings sake...what symptoms would I see IF the knock sensor was bad? (Besides a code)

Greeny

iTrader: (43)

This is in the stickies ....http://forums.maxima.org/showthread.php?t=396706

Greeny

iTrader: (43)

Main symptom of bad knock sensor is a lack of power under 3500rpm...

Wiking

I think engine dying is different from intermittent misfire: misfire means one or more cylinders dont get spark (points to coil, plug). Engine dead means control for all six cylinders dead. Points to ECU or some elements which can cause ECU to stop working. Highest is voltage supply.

All maxima computers need pwr: that is why checking voltage supply is the starting starting point. It has to be 13.8V-14.6V.

Connections collect oxidation and may cause anythin; I've tried to point out howto on may cardomain page. One possibility is worn ign switch that drops pwr supply from ECU: just swapping the sw, or making bypass wire to ECU. (ECU pwr relay also may have bad connection.)

vansskaterfreek:
U need a schema for tracing the ECU DC-supply, check c-domain Favorite Links (at left)

john93se

I'll look into it when I get home, CD is definitely blocked here at work. But it explains how to do the testing in decent detail? I'm not even sure where to start... Thanks for the suggestions

Wiking

Biggest problem is that its intermittent. How can u test a fault that is NOT tHere?

I would look/replace ECU pwr supply relay. Theres even one called ECU pwr supply safety relay in the drivers side rear trunk panel... dont know if it can cause problems. http://www.cardomain.com/ride/748507/15

As said, check the Links and you'll find also SE info - as my CD pages focus on VG. Still 'most' the same building blocks are found in both.

see http://www.cardomain.com/ride/748507/5

eric93SE

iTrader: (1)

well, most common problems with the ve are MAFS, injectors, coil packs.

Inspect all your coils for cracks or carbon tracings, if they have well over 100k miles on them they should all be replaced. If you have the fsm, you can monitor the voltage leaving the MAFS to make sure its functioning correctly, be careful hooking any probes up to the MAFS since its possible to short something out (ecu).

Also check your temperature sensor connector for corrosion.

john93se

Ok,

It's been 'diagnosed'... Anyone know where I can find the TSB for rerouting the engine ground? Couldn't find it on http://maxima.theowensfamily.com/tsb...=1993&tsb=none I'm going to try changing out coils, know of any places with good prices? Courtesy maybe? Anyway, I'm at work now and I'm going to pick it up tonight. I'll try taking a better look at the ground and maybe just change it out for ha has.