Stock injector swap now car will not run right

[TurboBuRick]

A couple times now I've run into situations where injectors have been replaced and the car will not run right. Yesterday I was contacted in an attempt to fix a car that just was just that. Car had been at a Buick dealer and had some things replaced to the sum of $3000. Injectors, fuel pump, o2 sensor and mass air sensor all had been replaced. Nun the less the car was given back to the owner not running right at all.

The motor would constantly hunt up and down at idle. Like the IAC was lazy and constantly chasing it's tail. Also had a pretty bad tip in stumble. Very strange. After swapping various parts I was scratching my head. I then then started to think about what the Buick dealer did. I've learned over the years that when all else fails it's time to go back over things that were done by others.

I finally figured it out but before I reveal the fix does anyone care to take a stab at what it was?

Rick

 

[DarthBuick]

Injector plugs swapped, Vac leak or MAF reversed.

 

[jasjamz]

They put a stock chip back in.

 

[TurboBuRick]

Injector plugs swapped, Vac leak or MAF reversed.

Not quite that simple but your warm.

They put a stock chip back in.

The new injectors are stock so the chip was never swapped.

 

[Royal-T-Ltd]

Bad replacement O2 sensor?


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[pdzz]

Left the collars from the old injectors in the intake. Phil.

 

[TurboBuRick]

Bad replacement O2 sensor?


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I was on that same page. The O2 that was replaced from the dealer was a Bosch. I replaced it with a denso which made no difference.

This one is not a very common problem or at least you don't hear much about it. It's something that's easy to overlook and I'm betting there are a few cars out there with this scenario.

 

[TurboBuRick]

Left the collars from the old injectors in the intake. Phil.

Nailed it Phil!

 

[pdzz]

Seen that one before! Phil.