ECM Reprogramming VG33E

[berge]

I have a 99 Quest with the VG33E. Has a strange problem. It feels like the throttle is sticking while driving. If I'm in a traffic jam, everyone else is rolling off the brakes and I'm the only one on the brakes. Same at steady speed cruise, I let go of throttle and vehicle maintains speed like cruise is on.
Park and Neutral, there's no issue. Rev up and it comes down nicely to base idle no problem. Only when driving is there an issue.

I've cleaned out the throttle body, no codes, everything to spec and tune-up done. I have alldata subsription which shows TSB #00-006C date oct.6,2003. 'ECM REPROGRAMMING'. But it doesn't explain why, just the actual service procedure.
Anybody know, had it done, experienced something similar?

thanks.

 

[brianl703]

Not all TSBs are about a problem. Some provide training.

They may have issued that TSB because dealership level technicians were not familiar with or needed clarification about the ECM programming prodcedure.

 

[berge]

ok. here's a better description.

when getting off throttle, idle sticks around 1200 rpm and stays there until vehicle comes to a complete stop. then goes down to normal 750RPM idle. problem seems intermittent. It feels like it's doing it at highway speed too (sticking at a higher RPM) but I'm not absolutely positive about that one.

so basically, there's an issue with the engine dropping back to idle off throttle.

sorry, this is the best I can describe it.

thanks.

 

[berge]

quote:

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Originally posted by brianl703:
Not all TSBs are about a problem. Some provide training.

They may have issued that TSB because dealership level technicians were not familiar with or needed clarification about the ECM programming prodcedure.

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understood. thank you.

 

[brianl703]

That sounds like a sticking idle air control valve.

Some can be cleaned.

 

[berge]

quote:

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Originally posted by brianl703:
That sounds like a sticking idle air control valve.

Some can be cleaned.

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wouldn't a sticking IACV show at Park/Neutral too? I can rev this thing all day long and it always comes back down to its proper base idle.

 

[brianl703]

quote:

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Originally posted by berge:
wouldn't a sticking IACV show at Park/Neutral too? I can rev this thing all day long and it always comes back down to its proper base idle.

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Quite possibly not, there isn't any need for the computer to change the IAC setting from where it was before you revved it up in neutral.

When you're actually driving it, the IAC is most likely opened fully so that when you take your foot off the gas, the computer can gradually close it so as to provide a smoothly controlled application of engine braking, and then open it up again as engine speed approaches idle. I know for a fact that Ford vehicles do that.

Any IAC sticking will show up during these wide-ranging changes in the opening.

Have you tried disconnecting the battery? Sometimes strange idle problems can be fixed by doing that.

 

[berge]

yes, I've already disconnected the battery.

what you're saying re IACV makes sense. I'll get out the service manual, clean the valve, and report back.

thanks.

 

[berge]

quote:

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Originally posted by brianl703:
I know for a fact that Ford vehicles do that.

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I know the engine/transmission in this van are 100% Nissan and all else is Ford. Assembled in Ford plant. I've always wondered whether things like IACV valve, ECM, TPS, things like that we're Nissan or Ford parts.

 

[brianl703]

Well, this is really a matter of programming, and it wouldn't suprise me if it is a standard feature in fuel injected vehicles from all automakers. In fact, it's such a simple operation that I'd be surprised if it weren't.