Strange problem with my old IS220d

[Shahpor]

Hello all,

I was wondering if anyone had any experience/idea's on what could be wrong with my old IS (Which I sold to a friend of mine). 

Basically, from cold it has real trouble idling, with the revs bouncing up and down and the car almost stalling, which gets a little better when warm but it still not a smooth idle.  Also, it will misfire and judder on light throttle between 1000-2000rpm.  It seems to go ok when under heavier load.

It did throw up an error once and go into limp home, so my friend called a mechanic that said it was the EGR valve and replaced it.  When that didn't solve the problem, he thought it might be a faulty part so changed it again - same result.

I had a look at this and plugged it into techstream.  No fault codes, but I did notice that the pressure of the MAP sensor was dropping into the 50-60 kPa whereas the manual states that it should be between 85-93.  So, I fitted a new MAP sensor today.  Everything seemed to go well (with the pressure a little over standard in the late 90's) and importantly the car idled smoothly and revved with only the occasional stutter.  However, after 3-4 hours my friend went for a drive and it has reverted back to how it was.

I am not sure what to suggest next, so has anyone got any ideas?

Thanks.

[Mihanicos]

Check the fuel pump delivery pressure. Then check the fuel pressure to the injectors. If they are ok, have the injectors checked by a specialist. 

Chris.

[Shahpor]

Thanks Chris.

Will have a look and see what the pressures are.

Unfortunately, owing to the low value of the car, it is probably not feasible for the owner to have the injectors checked, which is annoying as I believe it is a good car.  The problem is, at 12 years old and 163,000 miles, he believes it might be the start of more problems that wouldn't be cost effective, so if the fix isn't cheap then he will probably move on.

[johnatg]

I suspect there is a problem with the wiring or plug to the MAP sensor. Maybe internally in the wire at the first tight clip or in the plug - poss a poor joint between wire and terminal.

You've wiggled the wire and that fixed it temporarily, then it failed again. Try more wiggling but it will need a permanent repair.

Of course I may be completely wrong.

But many sensor problems are really the wiring - a lot of perfectly good sensors get chucked away.






Sent from my PSP7551DUO using Tapatalk

[Shahpor]

The does sound promising John.

One strange thing I did notice was that one of the bolts that holds the sensor in place was missing, suggesting someone had been playing in that area at some point.

He is going to bring the car over to me soon to check the fuelling, so I will add wiggling the wire to the list and see what happens.

Thanks for the suggestion.

[m4rkw]

Where did you get the replacement MAP sensor? New doesn't always mean working..

[Shahpor]

Funny you should mention that Mark as he has now fitted another new EGR valve and it seems to be running better.  The last 2 were supplied by the mechanic but he bought this one himself, so as unlikely as it might sound, it could be that the 2 valves he got from the mechanic were faulty.

Hard to believe, but time will tell if the car continues to run properly..

[m4rkw]

This kind of thing is actually more common than you might think, I’ve heard stories that from some manufacturers brand new OEM parts often don’t meet the manufacturer’s own specifications and have to be sent back. The average DIYer has no way to test most stuff so would never know. With aftermarket parts it’s probably even more common.

[Shahpor]

You could very well be right about this.  After all, it is reasonable to assume that the mechanic bought both of his valves from the same place, ergo same supplier.  Along comes a different supplier, with potentially a superior quality part, and problem appears solved.

The funny thing is, he only bought the last valve because the mechanic offered him a refund if he returned the supplied valve, so the car could very well have ended up being part ex'd for a few hundred quid on the assumption that something else was wrong.  As it turns out, there might be more life left in the old girl yet.