Backfire out of 20v BT ITB's

[danniboi88]

Last year I rebuilt my 20v blacktop motor but didn't change out the pistons, valves, or valve springs. Did a whole overhaul, had TODA cam shafts 264 with a 9mm lift running off BT ECU, TODA cam gears, new knock sensor, O2 sensor, water temp sensor, and COP system. Everything ran fine during the break in process and ran up to 2000 miles within 2 months. One day on the highway I was going 70mph, it started bogging and sounded like a lawn mower. Each day passed by, it got worse, and ended up not starting anymore.

I've replaced the O2 sensor, water temp sensor, misc items like fuel pump, fuel filter, spark plugs, replaced oil and oil filter. Tried my ECU on another 20v BT and my ECU worked just fine. Harness was done by Dr. Tweak. I noticed I don't have a one way valve going to the MAP sensor, PCV valve, EVAP purge solenoid, or a throttle diaphragm. Ran fine without them so I'm mind boggled.

I assumed a head valve was messed up so I ended up replacing the head to a fresh machined stock head. Still won't start and still have flames coming out of my ITBs just like when I had my other head on. I assumed it was a sensor and replaced randomly the TPS. Only thing I haven't replaced is the ISCV but ran out of funds and just need assistance or advice. No check engine light. I don't think it's even hooked up. I read somewhere if the wiring to the distributor was wired incorrectly, that it would cause the backfire in the ITBs. If it's true, how would I go about that?

All I'm really asking is for someone to come over and take a look at it and spew their knowledge and make my car running again. It seems like it's been 3 years of this car sitting around and actually only been able to drive it a whole 2 months. Definitely don't know of any shops that deal with 20v BT in the DFW area. Once again, any advice is much appreciated.

**UPDATE**
7/04/2012

I was messing with the distributor and with Wide Open Throttles I was able to get it to start; however, I can't get it to idle. It dies once it reaches approx 1700 RPM. I sprayed carb cleaner down the ISCV (probably didn't do anything) and still doesn't idle. I'm not sure which way retards or advances the timing when messing with the distributor. Is it possible I still have a sensor problem? I plan on replacing all my vacuum hoses in case I have a crack or leak somewhere. Any other advice would be much appreciated. Thanks in advance.

[mandm177]

they way that you describe it definitely seems like a timing issue to me...though when McKenney and i were discussing a bit, i'm wondering if the wiring might be a bit messed up.

I just really need to go over to your place one day and take a look see.

Did changing out the TPS sensor do anything for you?

[danniboi88]

No the TPS didn't do anything. I got a fuel pressure gauge and I was at 40 PSI the whole time. I can't rev past 2000 RPM unless I sloooowly give it more gas. The highest I got was 3000 RPM. If I were to suddenly try and give it more gas as if I were trying to get to 7000 RPM, it would choke and the engine would die.

As the RPM goes up, isn't the pressure suppose to go up also? Like I said, stayed at 40 PSI the whole time.

Anyways, Angelo has reason to believe it's my FPR so if I got the cash, I'll get a new one and maybe that'll fix my problem.

[mandm177]

hmm...before you do that, i need to bring my car over and we can test my FPR. it should be a simple swap to see if it works or not.

so it sounds like you're able to get it idling now...get someone to turn the Dizzy while you press on the gas and see if it makes it any better.

Also, do you know what condition your COPS are in? i have an extra set that i can bring over to test as well.

[danniboi88]

oh it still won't idle. I just keep my foot on the gas to keep it from dying.

my COPS has 2000 miles on them plus lots of cranking the past few days.

[danniboi88]

Thanks Mark for letting borrow your 1NZ coils. Apparently my 1ZZ coils were either going bad or not enough distance to create a strong enough spark. Besides I don't know how old those 1ZZ coils were or how much mileage were on them before. I'm assumed they were new but who knows.

ALSO, the hose connected to the bottom of the ISCV was too small of a diameter to keep the car at idle. I took the filter that was on the end of the hose and slapped it right on the ISCV without the hose. Now it idles at 1000 RPM and can actually drive. No popping, no miss firing, no flames out of the ITB's; however, it seems to lack power. Going to mess with the dizzy/TPS sometime this week.

I'll post up some pictures of my set up in the near future or whenever I'm not lazy. Hope this helps anybody with 20v engines. AND I can't thank you enough McKenny for helping me swap my head and oil seals AND Mark for letting me borrow those parts. I'll give them back, I promise XD

[mandm177]

im still curious to know why your dizzy is pushed all the way to the 9oclock position (looking at it from the radiator) in order for it to run better. It just seems to me that your exhaust cam timing might be a tooth off or something.

If you want, you can take off all of your front engine covers and make sure the Cam timing is spot on again. make sure the dimples on the cam gears are near 12oclock and also facing each other (intake a 3 and exhaust at 9), and when you look at the oil gear behind the bottom cover, make sure the dimple is near the 2oclock position lined up with the dimple on the block.

In any case, at least we got it idling, and found that the COPS were a part of the problem and that you can drive it again!

[McKenney]

No problem bro. I know for a fact the cam timing is spot on Mark.


Daniel, give me those tension rods!!!!

[danniboi88]

Since Mark's Toyota Denso coils worked, I ordered 1NZ coils 90929-02240 and I got some STI yada yada which had the same part number as the Toyota Denso coils. The STI 1NZ coils were cheaper, and I thought it would be the same. The connector never seated on the STI coils! Then I was like whatever, I'll just shave all 4 down and just test it out with the connector snug, but not fully seated. My car ran like shit, bogged, and wouldn't idle at all unless I had my dizzy all the way advanced.

After that incident, Mark let me borrow his Toyota Denso coils with the SAME PART NUMBER 90929-02240 for the time being. The car runs just find with Toyota Denso coils.

My recommendation is not to get new STI 1NZ coils for your 20v engine. I'm going to order some Toyota Denso coils one day and I'll keep you guys posted. Sorry no pictures yet. Obviously Mark's 1NZ coils are amazing. Wish I didn't have to give them back.

[McKenney]

I think I have this handled. We'll see when Daniel gets here.

[Milhouse86]

Been having a similar problem with my bt it revs to 3.5k and cuts out / backfires feels kinda like a fuel cut. If i rev it sliw it will rev past 5k sometimes and just like danniboi just started happening and steadily got worse ive swaped coils from honda coils to 1nz coils even tried two different computers. I just pulled the front covers and the timing belt is dead on.

[danniboi88]

Sorry for not replying after getting the problem fixed. It ended up being my coils. Aftermarket coils are a no bueno. Definitely go brand new OEM coils since that was the actual fix for me. It cost me a pretty penny, but my car is up and running. I would also recommend changing out those spark plugs as well.

Milhouse86, I wish you the best of luck. I have a feeling it's still a combination of coils and spark plugs.

If you got an ISCV, I would make sure it's clean and still operates. I used to have a hose with a filter, but the hose was restricting the air to the common vacuum do-hicky so it made it lag. The backfire is probably getting too much fuel and not enough spark to burn off the excess fuel, which makes it more difficult to start the car if the spark isn't strong enough to actually start the engine.

[Milhouse86]

It starts and idles fine just cuts out. The front of the motor is apart right now at my work but gonna put i back together to check fuel pressure, compression and timing.

[danniboi88]

It starts and idles fine just cuts out. The front of the motor is apart right now at my work but gonna put i back together to check fuel pressure, compression and timing.

I seriously thought it was a timing and compression issue also for my car. It could be the case for you, but replacing my head to a stock BT head, making sure compression and timing was on par, and fuel pressure was good didn't fix the reving past a certain RPM. It was just spark plugs and new coils that fixed it for me.

I'm assuming you've already tried messing with the distributor in the back to retard/advance to see if that does anything.

Anyways, hope you get your BT up and running.

[Milhouse86]

No not yet but i do have denso coils but there from the junk yard and worked well but changed them out cause the 1nz or 1zz coils i had on gave me a 6.5k rev limit and the honda coils gave me an 8.2k rev limit but i have my problem with both couls