Backfiring? under boost

[chet1185]

I don't know anything about this car yet. bought it as a fixer upper. 6 bolt swap, kiggly kit with 2g trans.

Just got it up and running. front and rear motor mounts are bad, motor flexes to firewall and ac pulley rubs frame. Just changed the front and it fixed it halfway, so I'm ordering the rear now. But to the issue here.....I'm assuming as the boost builds, the car backfires. If I slowly raise the rpm's while cruising it just takes a little longer to do it. It is the stock exhaust so it kinda sounds like a pop and the car jerks a little. Feels like the bakes are being hit on and off. Sometimes if I'm WOT, the rpm's go up smooth but other times its rough.

Only thing I did to the car was the stock boost controller mod. Don't know if it has a boost leak or anything which I'm sure I'll have to do before anything else. Spark plugs look brand new but I didn't check the gap on them. Read about fuel cut off but I don't know what that is exactly.

 

[dakang]

might as well do the boost leak test first. you can easily end up throwing cash at this car without checking that first. I would check the spark plug wires as well for arcing as well

 

[chet1185]

Ok ill check it out. Can you make your own boost tester? Or would an ebay 1 work?

 

[mjdarg]

As mentioned, I would do a good boost leak test to see if you have any leaks anywhere. How does the car idle (warm/cold)? Fuel cut is when the ecu can't supply enough fuel for the incoming air. Instead of letting you run lean, it cuts fuel for a bit for safety.

 

[chet1185]

Car idles weird. Stays at 1500 then goes to 2000 then back. Keeps doing that. Sometimes it idles fine. But not often. I just got a used iac, tps. Car doesn't have an evap solenoid and the mdp is not hooked up because of the 6 bolt swap. It is plugged it though. Have an engine light for the MDP and EVAP. I just got an evap solenoid also but my pigtail is round and the evap is square.

 

[99ECLIPSEGSXDSM]

When's the last time the maintinance was done? Check your spark plus and wires as well when you do the boost leak test.

 

[chet1185]

Ill order a tester. Does anyone know the diameter of the stockt25 inlet?

 

[athlete3344]

http://www.dsmtuners.com/forums/new...urbo-spins-cant-find-issue.html#post153410569

See post for DIY BLT vid.

 

[dakang]

Check this link for the tester you can make.
IC Pipe Tester

 

[smills1840]

Check to make sure your MAF is clean and plugged in. Then do as the other guys suggested - boost leak test, fix any boost leaks, new plugs and plug wires, etc.

Keep up with the small maintenance things before they come back to bite you in the ass.

 

[Joethefallen23]

Could be spark blowout. You mentioned they were New plugs but not what brand. If it's the common Bosch platinums that every chain loves to push on these cars, there's your issue. These engines really only play nice with plain old ngk coppers bpr6es, 7es, or 8es depending on what your setup is. The more lbs/min the colder the plug.

 

[smills1840]

You want brand new NGKBPR6ES , gapped to .028".

 

[chet1185]

Is that the ngk 7131 standard copper?

 

[dakang]

yes 7131 is the part number

 

[chet1185]

Thanks

 

[chacedog1]

also for the hec of it check the intake pipe that the clamps and couplers are tight on them and no cracks. I had a cracked intake pipe before and had similar issues. Un metered air was coming in causing problems and back firing issues.

 

[chet1185]

Ok, ill look into that also.

 

[1G Eclipse94928]

Sounds like fuel cut...
Vid.

 

[chet1185]

Would i. need a fuel pressure gauge to see fuel cut?

Are ngk 8100. wires good?

 

[codym]

A wideband would tell you if your spiking lean due to fuel cut or rich due to a boost leak, but if you haven't put a different turbo on than it is probably associated with boost leak. The air that is already monitored is getting out somewhere,
Fuel cut will make you crap your drawers, a boost leak will just jerk you around.

 

[chet1185]

I'd love to have one. But can't afford it right now.

As far as testing for a boost leak, do i have to have a boost gauge hooked up? I have 1, just didn't install yet.

 

[codym]

Not necessarily, you just need some sort of gauge on the tester to tell when you've reached your testing point, you should pressurize the system up to 20-25lbs, and if it doesn't hold you've got a leak somewhere.
The injector insulators that sit between the injector and block is a commonly over-looked spot, along with intake manifold and throttle body gaskets.

 

[chet1185]

It should be pressurized that high even though its the stock t25?

 

[codym]

If you're running stock boost levels, 8-12lbs, it isn't a bad idea to ensure the system will hold a few more lbs of pressure than what it will see during operation. If your system is leak-free at 20lbs, than it will be more likely to stay leak free at 8-12lbs.

 

[chet1185]

Ok. Sounds good

Anyone know the size of the spark plugs? I dont have a deep socket to fit it and i wanna check them before replacing.