misfires on boost 5k

[awdmonster1904]

car is an 1990 1g dsm

SETUP 20g at 30 psi on E85
1200cc all supurting mods


I would drive normal on the freeway everything is normal from 0 mph to 75 mph
if am easy on the boost

But if i go full boost to do a hard pull it will make a sputtering sound out from the exhaust and it does it right at 5k afr is at 11.7 to 12.3 and the sound are coming from the exhaust

at first i was thinking its was my rear end but i figured if my rear end was bad it would make noise at 75 mph or 35 mph in witch does not

i checked the plugs and the look normal they kinda look like the have a white film on them but its light

anybody that runs E85 on there dsm come across this issue?
any input would help



TIA

 

[jaycemocapaldi]

The cause is usually a vacuume leak in the intake manifold, throttle body or vacuume hoses, a defective EGR valve leaking exhaust into the intake manifold, bad fuel, bad plug wires, fouled spark plugs, weak ignition coil, dirty injectors, low fuel pressure or even a weak valve spring.
I would check the vacuume pressure with a vacuume guage. it should be between 16 and 22 if lower you have a vacuume leak, find the leak and fix it. If you are running a cat in your exhaust, make sure it is not plugged as well.

-I hope some of this can help, it took me forever to think of all these reason's haha. If i think of anything else i will post again, good luck!

 

[awdmonster1904]

If you are running too rich this could happen. when was the last time you were tuned?

the car is been tuned and dialed in good its been rining good for the last year
its tuned on ecmlink also the afr are at 11.7 to 12.3 It does not seem to be runing rich

 

[jaycemocapaldi]

Ok well, if it is not running richly then the cause is usually a vacuume leak in the intake manifold, throttle body or vacuume hoses, a defective EGR valve leaking exhaust into the intake manifold, bad fuel, bad plug wires, fouled spark plugs, weak ignition coil, dirty injectors, low fuel pressure or even a weak valve spring.
I would check the vacuume pressure with a vacuume guage. it should be between 16 and 22 if lower you have a vacuume leak, find the leak and fix it. If you are running a cat in your exhaust, make sure it is not plugged as well.

-I hope some of this can help, it took me forever to think of all these reason's haha. If i think of anything else i will post again, good luck!

 

[awdmonster1904]

*update*
I checked my plugs and they still look good what I did see is the gap on the plugs was at .32
So I closed the gap to .20 for the boost that I'm ruining I figure I close up the gap
It help a bit but it's still does the sputtering at 6k
Also checked vacuum its all good

How can the EGR affect it what is there no vacuum lines connected to
Would that make it mess up well I figure if there no vacuum lines connected it would not open up

Has anyone had this problem on a car runing E85 ?

 

[awdmonster1904]

*update*

Parts I have changed

new plug wires
new plugs bpr7es gapped at .19
Fp intake

I took it for I drive no missfire Whats was strage is that I never adjusted the boost controller and it went from 30psi to 25 psi boost leak ?? maybee ......

Another issue, I Turned up the boost 4 turns and the boost still around 25~26 psi
also The car makes a miss fire noise at 7k

 

[TSi Kid]

You have the egr just unhooked?

 

[awdmonster1904]

You have the egr just unhooked?

the vacuum lines have been removed but its still connected

 

[awdmonster1904]

**update**
I finally got a chance to do a boost leak test
And yes I have a massive leak
I will fix the leak and see what happens next

 

[awdmonster1904]

**Resolved**
after all it was a boostleak and clogged up filter
That was causing all my boost issues

 

[LiquidX]

You wouldn't happen to have a log of the misfiring issue you had? If you do I just want to compare it to a log I have that I'm working on figuring an issue out.

 

[gofer]

Scott I've got a misfire log that was a boost leak issue but its on Speed Density and E85 if that matters?

 

[awdmonster1904]

You wouldn't happen to have a log of the misfiring issue you had? If you do I just want to compare it to a log I have that I'm working on figuring an issue out.

Yeah I do pm me if you still need it

 

[awdmonster1904]

here's there the logs when my car was all mess up

 

[REDspydergst]

back from the dead, sorry im having a very similar misfire right at 5k and im wondering what filter did you replaced. the air filter or the fuel filter? Thank you.

 

[LarryJoe]

I'm guessing fuel filter.