popping and backfiring in 4th gear

[gunzandgearz]

I'm with Michael Evans how can you be in 4th gear and just coming off idle does that mean it is in overdrive but you AR leaving from a dead stop so the transmission would actually be in first if so this is a lean stumble just like carburetors get when the accelerator pump isn't working they stumble,sputter and will slightly backfire, need a little more clarity

 

[gunzandgearz]

Your injectors could be partially plugged from sitting you might try putting some bg44k injector cleaner in the tank and see if this helps it any don't try any of the rest of the injector cleaner this stuff is Bar None the best you will have to look around to find it as BG only sells to shops as far as I know

 

[jpal]

modifications are 3" pypes exhaust,no cat,3"cold air intake with 3.5" ls1 maf and translator.afpr,50 lb injectors,power plate,and cx racing t66 turbo.i have no idea about the internals of the motor or tranny.the popping and backfiring is occurring while driving the car and the tranny is in fourth gear.if I let off the throttle and let it go back to idle,no foot on the pedal and the car is just rolling say at 55 mph and I go to push the throttle back down,foot on gas peddle,as soon as I start to push on peddle,it will pop and or backfire,if I let off its fine or if I push the peddle down further,it will clear up and is fine.only does this in fourth gear,does not pop or backfire in any other gear and does not do it under boost.i will disconnect actuator rod today and check wastegate.thank-you everyone for helping out.

 

[NY Twin Turbo]

Excuse me, I was just briefly skimming through.

Are you saying that if you are in OD (and only in OD), and cruising, and you lift, and then softly re-apply throttle, it sputters and backfires?

Could your converter still be locked up when you re-enter the throttle? What are your RPMs when you are just beginning to re-apply the throttle?

It sounds like a tip-in fueling issue. It's lean. But just at that point. Transitions at tip-in require additional fueling that used to be there, but no longer are. Now we just have to figure out why.

Can you add a bunch of base fuel pressure (say 55lbs) for just one quick ride and see if it goes away? Then come back, turn the pressure back down to normal and then start your search? At least you could verify it's a fuel issue.

Start biting off one simple thing at a time.

 

[jpal]

yes,it is only doing it in od,just picking up throttle.so on my scanmaster,it says 4th gear,if im on the throttle "tcc"comes on next to 4th gear on scanmaster,then if I let off the throttle "tcc" goes away,but it still says 4th gear.does "tcc" mean the converter is locked up?i didn't pay attention to rpms when re-applying throttle and don't think I will be able to get out today or tomorrow due to snow!!!!!!It does have a tt tweak chip that came with the injectors,maybe it needs re-programming?

 

[Pronto]

Please, it's "pedal" not "peddle". So, does it do the same if you have the shifter in 3rd? You could unplug the lock up on the trans to see if it's a converter lock up issue of not releasing. As far as the boost goes, I would not trust that Chinamade turbo. If you don't know if you have ported heads and a larger cam then a 66 is way too big anyway. Probably would take a week for it to spool, even a good brand one.

 

[No disintegrations]

How about if you get the rpms and speed higher, say 70mph and repeat pedal on and off. Still do it?

 

[jpal]

yes it does

 

[ScottHeidinger]

Is the chip burned for that turbo? I agree with what was posted above a 66 is too big for stock heads and cam. That’s probably why you have spooling issues. Probably better off with a stock or little bigger than stock turbo. Try unplugging the electric connector at the trans and see if you still have the issue.


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[jpal]

i just went and checked the turbo and on the compressor it is stamped t-6,not 66????the chip and injectors were bought used,so I don't know what it is burned for,the turbo is what was on the car when I bought it.i know it is a cheap turbo,but I wont be able to replace it till winter.i will try unplugging connector on transmission.it does not act up in 1st,2nd,or3rd gear.thanks again for all your help

 

[ScottHeidinger]

There’s a number on the chip and Eric marshal should be able to tell u what it was burned for. Most likely the chip doesn’t match your combo so the cheapest way out is to get the right chip but I would replace the turbo first because it’s probably not a good match for your combo.


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[jpal]

thanks,i will check with eric,as far as replacing the turbo,its just not in the cards right now,i am out of money and time right now to do any major projects till winter.other than poor performance with this turbo,if i run the car this year with this turbo,can i hurt anything in the motor or transmission?

 

[Pronto]

Well if the shitty china turbo decides to commit suicide and the chunks get ingested...

 

[NY Twin Turbo]

Guys let’s just wait a minute before digging into his combo and telling him what’s wrong with it.

If the stumble and backfire wasn’t there before, and now it is, let’s maybe not get into his Chinese turbo, unknown injectors, or possibly unmatched chip.

The fact may remain that the problem was not there before And something happened that changed that. The first thing to do is find out what that thing is.

 

[gunzandgearz]

Yeah I'm with Joey on that you need to make sure the converter is not staying locked up as this will load the engine and demand more fuel on tip-in as he said but first let's see if the converter is actually getting the signal you can get on the highway barely touch the brake pedal just enough to turn on the brake lights not enough to stop the car you should feel the converter disengage and then let up off the brake pedal then it should re-engage you will feel is almost like a shift now we know we're getting proper signal of converter working okay but I would still unplug it just to see if it goes away if not as I said in one of my previous posts if this is a problem that has just come on from it sitting sometimes the injectors will get just enough trash in them or gunk to where they won't spray properly as you tip in on the throttle use a can of bg44k find some supplier that might have it in your area usually auto repair shops and just try it all these are good suggestions but if the car wasn't doing it before and now it is it obviously is not from the parts that we're already on the car

 

[jpal]

thanks guys,i will try that,not sure i will get out today due to weather,i will let you know what happens.