backfire in 3rd

[crazygn]

I seem to be getting a backfire when racing in 3rd gear, load too. This is the 2nd time it done this now. Iam running 790's on my o2's in 3rd gear, this is where i want to be right. Iam also running 20-21 psi on 93 pump gas But iam getting no knock , maybe the knock sensor is not picking it up.

If i tap on the knock sensor or by it pretty hard it should pull up knock right. If not it a bad sensor i guess.

I did beat a old fast back mustang when it back fired by 3 cars easy. hope i have a head gasket left to do it again

 

[REDS HOT AIR]

out the intake or exaust??

i take it it runs better now...

 

[crazygn]

it sounds to be thu the intake ., real load It ran pretty good but then it back fired. I think its the cool air we been getting, plus if i had the money to put some cam2 in it i think it would wake it up some to.

 

[REDS HOT AIR]

out the intake is usually a lean condition watch 02's rael close and fuel pressure if you got a gauge you can read while driving.

it may have when lean and popped quick enough your scanner didnt catch it.

most all missfires or rich pop goes thru the exaust.

 

[crazygn]

Ok , i put some 50/50 cam2 in it today and so far its ok. Pulls a good bit harder with the 110 mix. I have a problem that i could never fix , it been there since i bought the car, it trys to stall off the light if i give it gas . I need to hold the brake and give it slow gas to get it to move but then it fine after that. Ive try to set the iac and it gets close but not where they say it should be .

If i can get it to get off the light it will be at the track friday night, just to see what kind of mph i can get because i still have the 1800 stall in it. Maybe try 23-25 psi and breing the turbo to life.

 

[crazygn]

oh yea where do i want the o2's at in 3rd at wot. They where at 790's last i checked.

 

[REDS HOT AIR]

scanmaster in the 780 range or alil higher
some scanners vary like with snapon scanner i shoot for 820's

sounds like them comp lifters were junk huh..

 

[crazygn]

Well sometimes it runs good. I ran the guy down the road today with his vett with little work done and i could not pull him it was dead on race. I then checked my o2's and they were in the 880-890's .

Since then i put new plugs in gaped at .35 and the longer push rods back in, also some 20-50 oil and oil filter. Its in the 50's now and i just got done eating a 70-72 chevelle up by at lest 8 cars. I guess that noisey gear drive he had just kakes it sound fast.

man i need a stall, or my trans fixed.

 

[crazygn]

I forgot, when i checked my o2's my t link will just say 50 , now what its a new o2 sensor put in today. I put 5 gal of 110 cam2 in with 7 gal of 93 and it started to read crazy and back fire when i was running it hard so i changed it with the new one. Now no backfire but its reading crazy, o2's where at 780-790 but it droped to 50 on the scan tool and 37* of retard , this cant be right.

 

[WFO]

do yourself a favor and buy a chip that idles in open loop.either a thrasher(good)or a maxeffort(by far the best).

i'm running a 16 pos maxeffort and my car idles nice and smooth(and i have hr poly mounts on both sides),no tip in stumble and you can tune everything.maxeffort chips run in open loop all the time,so there's no more worrying about fouling o2 sensors.tune with egt and knock and ignore the o2 sensor.money well spent,imo.

later,sean

 

[crazygn]

I'll look in to getting a new chip soon thanks for the info. Why would a new sensor read 785 on the o2's at wot then drop to 50 and stay there. Its a little hard to tune when i cant see my o2's.

 

[FJM568]

The lead in the race gas is fouling out your o2 sensor...

BTW, are you still running a catalytic converter???

 

[crazygn]

no i just run a open down pipe for the last year now. Iam going to do a compression test today i hope , this car seems to seems to pull less and less when i drive it. It pulled ten times harder at 17psi when i first put it together then at 22psi now.