Breaks up at 5500 rpms ??

[RedEyeBanDiT]

I have a 93 laser awd turbo, and for mods i have a k&n, 3 inch turbo back straight pipe, and a 16g turbo. everything else is stock.

at 5500 rpms in 2nd gear it breaks up and back fires blowin sum black and blue smoke, (mostly black) that is when i let off and just cruise after. but it has done it in other gears at that rpm.

so the other day i disconnected the vacuum line to the stock fpr and it would do the same thing at 5900 rpms.

I am running wastegate pressure, no more than 12 lbs of boost. and my o2 sensor housing is ported as well.

Thanks if you guys could help.

 

[crimsondragon]

What plugs you running?

 

[RedEyeBanDiT]

No idea, i never changed the plugs cause it always runs fine and never misfires. it still runs fine but just pops and backfires at 5500 rpm. i think its running lean

 

[stefanOst]

Do you have a good boost gauge to read what boost you are at? If you're running the 16g without any upgrades to the fuel system, it could be that the stock fuel pump and injectors can't keep up with the increased amount of air. But wouldn't black smoke out the exhaust be more of a result of a rich, rather then lean condition?

 

[Killa_dsm]

What plugs you running?

x2

If I were you I would check the condition of the plugs and replace them. Get some NGK BPR6ES and gap them to .028

 

[RedEyeBanDiT]

WORD about the plugs thanks.

I thought that was odd how it blew black smoke and pop and farted at 5500rpms.

 

[RedEyeBanDiT]

JUST CHECKED PLUGS AND THEY WERE BOSCH WR8DP, equivalent to ngk's bpr5es.

My compression is 165lbs across the board. YES 165 pounds.

 

[crimsondragon]

Why are you running such hot plugs? Get some NGK 6's.

 

[topchoice]

Let us know if that solved it. Well once you get those new plugs..

 

[lcvette]

I like the NGK BR7ES plugs gapped around .032" but for your boost level the 6's will be more then fine and not foul as quickly. can you verify your fuel pressure is rising with boost? I had some issues with this in tyhe past with a ruptured FPR diaphram and it caused me many restless nights of work trying to find what was going wrong.

keep us posted on it!

Chris

 

[v8s_are_slow]

Black smoke is rich. Need NGK's. If you're mostly stock, and changing the plugs (gapped at .028) doesn't fix the problem, you may wanna look at changing your fuel pressure regulator.

 

[Defiant]

JUST CHECKED PLUGS AND THEY WERE BOSCH WR8DP,

There's your trouble.

equivalent to ngk's bpr5es.

No they aren't. They're Bosch. If you have a very tall bridge near your home, see how good a splash they will make.
http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/233421-spark-plug-faq.html

If your wires are older than you can remember replacing them, get new ones.

 

[thom2white]

Yeah, seriously change and gap the plugs man, seen it a 100 times.

 

[RedEyeBanDiT]

Changed and gapped the plugs, it didnt break up and pop at 5800 rpms. But at 6k rpms you could feel a lil cough in the foot, but the rpms kept rising.

 

[crimsondragon]

Big improvement isn't it? You've seen the light.

 

[RedEyeBanDiT]

Honestly it runs the same but it doesnt backfire and pop over 5500 rpms like its gonna blow up. But I shift around 6k anyways cause it doesnt feel like theres any power up that high.

 

[v8s_are_slow]

You may still be running rich if it's giving you a problem at 6k. If it's still running rich, it'll get worse as the plugs get fouled out. Would help if you knew your air/fuel ratios or had a logger so you could know what's going on and better diagnois any problems. I'd say give it a lil while (week or less) and pull the plugs to check them again.