Turbo Backfiring
 

i changed my exhaust system to a 3in downpipe, test pipe and a blitz cat back...the car runs fine but when the turbo builds up pressure, that when i get a jerk...the gauge used to read at -4, now it stays right above the 0mark, exactly above the 0 mark...the gauge was reading and i saw it go straight to above the 8mark...its weird because the turbo seems to be building up more pressure, but gets to a certain point where it starts backfiring and the car starts jerking...also the engine light goes on only when the turbo acts up

any ideas?

yup, knock or a bad knock sensor. what diagnostic coss do you have? 52?

Idk dude, i dont have the computer to tell me codes and mechanic doesnt have 1 for an 89

i changed a rod knouck sensor before, could it be the other 1, or is there more than 2?

See following link to check your codes:

http://cygnusx1.net/Supra/TechTips/e...ror_codes.aspx

And yes, there is 2 knock sensors for 7MGTE.

If there's a code 52 the most common cause is bad wiring.

if its not?

:squint: Seriously?

Sorry to doubt in you cre lol. How long have u been with supra's?

Too long. ;)


I took your question to mean that if you have a code 52 and it's not the wiring then what else would it be... the answer is on the same page as the diagnosis procedure reydio so kindly linked to: If not wiring then all that's left (with regard to that specific code) are the knock sensors and the ECU.

Have you even checked for codes yet or are we still speculating?

still speculating...im going to do the paper clip thing and write down which codes i get...ill report back with that

I got codes
 

The codes i got are 24,34,14,41,43,42,51,44
im guessing thats alot of bad sensors or bad wiring

14= Ignition signal
24= intake air temp sensor
34= turbo charger pressure
41= tps signal
43= starter signal
42=Vehicle speed sensor
51= no such code
44= no such code

I would say from the codes above the accordian hose that holds your mass air sensor may be cracked or you have a boost leak somewhere.

Code 51 is signal switch error. I didnt get a code 52 or maybe didnt catch it. Should i still change my knock sensor, cre?

No I would'nt replace the knock sensor check for a vacume leak. I'm sure you pulled off some items when you installed the down pipe......did the down pipe you bought replace the o2 housing too? Clear the codes and drive the car and see if the same codes come back, some od those codes may have been old stored codes.

i think i mismatched the the vacuum line routing on the wastegate...no the downpipe just added an extra 02 bung for wideband gauges

I'm with MASSIVE boost leak + Push/pop starting a stalled car (or driving with a broken speedo cable and a bad distributor) + Stepping on the throttle while in diagnostic mode (that's your code 51, yes, it's a real code) + ..... well, something else.... <nevermind this bit.... no code 44 according to all the Toyota references I care to dig through at the moment..>.

These could all be old codes and you're just getting freaked out because you're hitting fuel cut and possibly over boosting. What's your AFR when the engine freaks and what is the boost reaching?

An O2 sensor wouldn't cause any of this, the ECU doesn't reference it at high loads.

And no, like Frisbee said, don't replace the knock sensor... see aren't you glad you stopped dicking around? ;)

i think i misinterpreted code 44, i only saw it once and i stood there for about 10mins, making sure i noted down the right codes. I don't know my AFR because i haven't installed the a/f gauge. The boost gauge is no longer working but when it was, it climbed over the 8+ mark and i was barely on the throttle, when i opened the throttle a little more, that is when i got the jerking action. Its definitely making more boost due to the bigger exhaust, i felt that from the start.

i was planning on upgrading my fuel system by a shop called e-shift performance. A guy that i know, who own an MKIV, told me that shop would get my supra up to par...as far as sensors and maintenance, what should i do? Should i get new sensors to replace the sensors that have reported error codes?

A tip.... it's hard to listen with your fingers in your ears.... ;)

I didn't ask if it was spooling faster or boosting a couple psi more... I asked WHAT IS THE BOOST!? and IS IT OVERBOOSTING?! Also, it's been *suggested* twice that you look closely for a BOOST LEAK. Quit questioning everything and grab a f#$king wrench and actually help us help you! Also, if you don't have ANY of the equipment required to SAFELY mod the car then DON'T TOUCH IT.





Okay... so, do we now have your attention? Take your ADD meds and get with it. If you're worried about your hands getting dirty go buy some gloves. Now start pulling couplers and looking for tears, inspect electrical connectors for signs of corrosion or poor connection. Go spend some money on some basic diagnostic tools and get some actual numbers.

You didn't wash your AFM with anything did you? They're easy to murder, NEVER try to clean a KVAFM. Just figured I'd ask as you're so sensor fixated.... A shot AFM could cause most of your problems, but they don't often die horrible deaths without some help.

i dont exactly know what you mean when you say "what is the boost?" its a ct-26 if that answers it and yes its overboosting for the stock setup.

im re-inspect the electrical and couplers, the only coupler i touched was that one on the turbo and that was still new as with all the other couplers that i replaced. What basic diagnostic tools should i be looking for?

No, i didnt touch the AFM.

i should also mention that the voltage test i ran on the batter stood at an averge of 13.9 on idle and 15V under engine load...when the car is running, the lights and anything electrical work just fine, but if i store my car for a bout a week, the battery would be dead.

i reset the ecu and got the same codes

Hey you guys
 

I fixed it! i had to reroute the vacuum that camr off the wastegate actuator. I also replaced the afm with an lexus afm to reduce fue cutl. Turbo spools up fine but my gauge doesnt work. Any ideas on why it doesnt work?