Chip Question

[1Gunner]

Last year I installed a Europroduct chip in my 87 911. I had previously installed a K&N powerflow, Borla SS exhaust and a Busch cat pipe with positive performance gains.
however....
Now with the chip, other than a 500 rpm increase in rev limit about all I notice is a huge intermittent backfire between 1st and 2nd gears on full and 3/4 throttle shifts.
Other than scarin' the $hlt out of proximate pedestrians, can/will this cause any long term harm to my engine or exhaust?

Has anyone had favourable results with similar setups.
I know this has probably been thrashed, but I'm new.

[WydRyd]

BTDT! CHIPS are useless in my experience.

Unless they are properly matched (on a dyno) to your other mods, I woudn't put much faith in any of them.

Trust me, I've learnt the hard way and even had to take a supplier to court for a tribunal hearing. Needless to say, they lost the case and I got my hard earned money back

If I were you, put your original CHIP back before you cause some serious damange to your 911.

Just my 2c worth.

[Steve W]

Sounds like your car has an air leak around the manifolds causing a lean condition when your throttle is closed. Thas can cause backfires in the exhaust. Check for vaccum leaks and loose bolts on your intake manifolds.

[masraum]

It seems I've read another potential cause of backfiring (besides the air leak mentioned above) and that is a too rich condition when you let off of the gas.

[michaelw]

Good timing on the ?. I just took my 87 carrera in to the shop because it was running rich (small puff of black smoke under hard acceleration out of gear). I also have a chip that was supposedly mapped to the car, K&N and upgraded exhaust.

Had mechanic check all sensors, CO mixture and idle. He said the CO mixture was way out of whack, something like 300 where it should be down under 100. Forgive me because I am new at this stuff and not familiar with the language. He said the chip would not allow him to get it under 150. All this was due to the setup causing an overrich condition. Too much fuel to the car. I also got an occasional backfire under hard acceleration while out of gear.

He did reset the CO mixture, lowered the idle and adjusted the timing a tiny bit. He said one of the problems w/chips, is that they push more fuel through the engine which could precipitate early destruction of the catalytic converter. Now the car performance wise runs about the same, but no more black smoke, no more backfire and hopefully less damage to catalytic.

He also said unless a chip is mapped to the car, it's useless.

Good luck,
Michael

[1Gunner]

Based on your replies, as well as my experiences, I'm must think the backfiring is because of an overly rich condition in the fuel mapping.
My fuel consumption had also increased quite dramatically once the chip was installed. Guess it's not a byproduct of increased performance, huh?

I guess I'll remove it tonight and chalk the $250 expense to experience. If it doesn't stop the backfiring, I'll check for intake leaks.....

Thanks for the various replies.