surging after gasoline

[JHZR2]

Hello,

Im trying to help a friend via long distance, so any insight would be appreciated. The car is a 2002 GTI 1.8T. Two weekends ago, we replaced the spark plugs. He changed the oil and air filter not too long before that.

I scanned his CELs, and it stated that there was a catalyst inefficiency issue and a coolant issue. I hit on those in another thread.

Today, a good time after, he sent aqn email stating that the car was surging. This occurred not long after getting gas at a local cheapo station.

He drives a lot, and he has a GTI, so Im sure that the gas has been refilled since we did the plugs. I cant imagine that new plugs, gapped correctly and torqued with a torquewrench could really be bad or a problem.

surging seems to me to be either a turbo issue, a fuel pump issue, or a sensor issue. Given that there was a cat efficiency code and I could only find voltage on one O2 sensor, I have to wonder if lack of control/running rich on bad/wet gas could cause such an issue.

Any thoughts??? apparent surging under load after getting gas. On a car with no coolant sensor and bad cat efficiency but fresh plugs...

Thanks,

JMH

 

[Steve S]

Fuel filter? What kind of sparkplugs.

 

[JHZR2]

Denso Iridium IX

Dont know if the fuel filter has ever been done in 129k. A batch of bad gas could be just what is needed to clog it real well...

JMH

 

[Steve S]

I forgot ...a bad sparkplug wire if it has them? I an just going over the very basics. Usually surging could be a lean condition . So whatever can cause a lean condition. No coolant sensor???.How does the comp know the engine temp?

 

[JHZR2]

no wires. when we pulled the coils, they looked good, not that this is indicative.

Perhaps something like a breather came loose. There was a pcv hose that was torn (it apparently is notorious on the 1.8T cars)

I wish he had the codes. Maybe Ill have them tomorrow.

Thanks for your help!!!

JMH

 

[mechtech2]

The stock computers on the GTI turbos are not very well programmed.

But this miss/surge is new, and since the O2 code is given, we have to start there. [New sensor , wiring, or connector is bad]

 

[mechtech2]

Obviously, the fuel could be all that is wrong - it is not uncommon.

 

[PT1]

Run a bottle of redline S-1 through the tank before you do anything.