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Old 10-12-2008, 07:35 PM   #1
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Default Problem when hitting 10psi, car seems to rapidly backfire

I have a 93 with a greddy turbo, rx7 intercooler, walbro 190, 02 clamp, 1.8 injectors, bipes, vortec fpr, dual exaust with no cat. Once I hit full boost I get what sounds like it backfiring very rapidly and my acceleration is pretty much gone. Any thoughts, it has been doing this for a few weeks and I can't figure out what's wrong. My first through was that it was rich, any thoughts.
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Old 10-12-2008, 07:41 PM   #2
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Install new NGK's BKR7's gapped to .020" and report back.
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Old 10-12-2008, 08:16 PM   #3
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Default New plugs

I just put some new plugs in about three weeks ago, but i will double check the gap.
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Old 10-12-2008, 08:58 PM   #4
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Which vortec disk? 10psi on bandaids is no good w/o a wbo2.
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Old 10-12-2008, 09:08 PM   #5
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BKR7E spark plugs.

If it's rich it feels more like it's just bogging down.
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Old 10-12-2008, 10:05 PM   #6
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way too lean will cause this condition... too rich bogs down and smoke...
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Old 10-13-2008, 12:31 AM   #7
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I'd say you are leaning out to the point of misfire. Been there done that, twas a bad fuel pump.
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Old 10-14-2008, 02:34 PM   #8
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Default Plugs Gapped at .020

Ok, I've regapped a new set of BKR7E's. I'm still having the problem, any other suggestions? Thanks guys.
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Old 10-14-2008, 03:18 PM   #9
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Quote:
Originally Posted by pdt602 View Post
I have a 93 with a greddy turbo, rx7 intercooler, walbro 190, 02 clamp, 1.8 injectors, bipes, vortec fpr, dual exaust with no cat. Once I hit full boost I get what sounds like it backfiring very rapidly and my acceleration is pretty much gone. Any thoughts, it has been doing this for a few weeks and I can't figure out what's wrong. My first through was that it was rich, any thoughts.
I thought 1.8L injectors were only good for 9psi? Back it down to 9psi and see what happens. If it runs smooth, I wouldn't run 10 again. Just me though.

What is your base spark set at?
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Old 10-14-2008, 04:04 PM   #10
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Quote:
Originally Posted by Toddcod View Post
I thought 1.8L injectors were only good for 9psi?

too many variables...


it's possible if with the 190 lph fuel pump and the 12:1 were used in conjunction, that it could be overloaded with fuel, and the backfires are the result of raw fuel making its way into the exhaust.
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Old 10-14-2008, 04:07 PM   #11
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-what's your air/fuel gauge say? That will take out some guess work.
-Are you sure your couplers are all tight and it's not leaking at a higher boost level?
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Old 10-20-2008, 10:29 PM   #12
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I checked all of the couplers and they are tight. I lowered the boost to like 6 or 7 psi and it seems to work fine. maybe I need to get some dyno time and tune it again unless anybody else has some ideas.
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Old 10-23-2008, 11:12 AM   #13
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Well, the best idea was already mentioned:

GET A WIDEBAND
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Old 10-23-2008, 02:35 PM   #14
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Without a wideband you don't have some of the most important information needed to diagnose the problem. It is likely caused by a rich or lean condition but you have no way to know which. With that information it would give you some idea of the source of your problem. It will then help you in making adjustments to your system and make sure things are still safe. It's a $200-$300 investment that will help you tune your system and possibly save your motor.
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Old 10-23-2008, 03:35 PM   #15
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wideband
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Old 10-23-2008, 06:21 PM   #16
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I vote over rich... I run a simular setup, with wideband... before with the 12.1 disk in the vortec.. afr would be damn near 9.5 -10 on WOT runs... this is running 9 psi... i havnt pushed my setup to 10 psi but want to when MS goes in...

When i would get near 10 rich...it would bog, loose and not pull like you thought it would... lightened the disk in the vortec to the 8 or 6 i dont remmeber.. and now 11.5-12 at WOT.
Have someone "follow you" are you sending massive ammounts of smoke Light colored out the tail? Does it smell alot like fuel? etc...

I would doubt spark blowout... are those backfires LEAN conditions? and your hearing detonation?

Just my thoughts

Goodluck
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