tpi Back firing. Please help
 

I have a 90 formula tpi with a 5speed. Couple days ago i changed the fuel filter then I drove a total of 500 miles for the 4th july weekend. Then on tuesday when i went to work it started to smell like gas was leaking but i couldn't find the leak but it really smelled. Hours later while in a stoplight I tried to accellerate when it turned green but it started to back fire and i couldn't go pass 2,500 rpm so i was moving slow on 1st gear. So i pulled over and checked what was going on. I turned the car off and started it up again and still the same. So I next open the gas cap to release some pressure and then I started her up again and it all went way. But this morning it started to back fire again but this time i go drive it pass 2,500 rpms with back firing in every gear. Could it be one of my injectors went bad? And how do you know which one it is? My car has 99,000 miles and Im the third owner and everything is all stock, no mods. My car is very clean.

Re: tpi Back firing. Please help
 

if you want to check the injectors you could begin by checking the resistance, if you have anything less than 10 or 11ohm and they are multecs,, dump them! To see if any of the injectors are leaking, just run the engine for a minute or two then pull the plugs,,,if you have a wet cylinder you have a leaky injector.

Re: tpi Back firing. Please help
 

Maybe your Cat. Converter is bad?

Re: tpi Back firing. Please help
 

If my cat. converter was bad my check engine light would be on right? It does not light up.

Re: tpi Back firing. Please help
 

Cat converter has no sensor so it would not trigger the SES light. Does the backfire exit the muffler or the intake? A backfire could be the result of bad timing. You got a 1990 so I dont know how to disable your EST. The point is you may want to check the timing via timing marks from the harmonic balancer. On my 86 IROC, I set mine at 6* with the EST wire disconnected. Do what SouthBay08 mentioned. If you do have a leaky injector, it may be soaking up the cylinder and ends up igniting when it shouldnt. This is dangerous especially to the cat because it can cause all the little tubes that look like honeycombs inside the cat to collapse.

Re: tpi Back firing. Please help
 

Second thought, look under the car and check if there is a wire coming out of the cat. Like I said in the prior post, Im not familiar with the 1990 Formula.

Re: tpi Back firing. Please help
 

let me correct myself. its missfiring. hp is not very strong when i drive it.lack of power.

Re: tpi Back firing. Please help
 

Missfiring. ok, well the issue lies somewhere in the ignition system. You may want to do the most common things first. Change the plug wires, spark plugs (use proper gap), rotor, cap, coil, ESC module. Any trouble codes such as a code 42?

Re: tpi Back firing. Please help
 

backfiring is probably caused by a lean condition. Since you smelled gas, it could possibly be a leak which will give you a lean condition. The fuel pressure regulator is one possiblity of a leak. It doesn't hurt to also check the ignition system as another poster said. You really didn't say where you smelled the gas from tail pipe or under the hood. So we are just guessing. You need to provide more details. But the backfiring you are experiencing is a lean condition. That you can count on.

You may have a bad O2 sensor...and yes, you can't always count on the ECM to trigger a code for that. A bad O2 senor can also feed the wrong info and cause a lean condition.

just need to provide more details.

Re: tpi Back firing. Please help
 

Yup. Our thirdgens are good in finding and alerting faults, but there are limits in the diagnostics. Example, todays cars can and will tell you which pistons are missfiring. Ours, hahahaha, time to get your hands dirty. Can always count on our diagnostics.

Re: tpi Back firing. Please help
 

Thanks you all for your help. I found the problem. One of the injectors went bad and I hope they come in today. I'm replacing them with bosch III injectors .

Re: tpi Back firing. Please help
 

happy that you found the problem. Bosch lll's.....good choice!

Re: tpi Back firing. Please help
 

Bosch III's!!!! Excellent choice buddy.:thumbsup: