SR20 backfiring under boost

Canada Nissan Automotive
1

hello. I have an S14 SR20 and lately it’s been running like garbage. I bagged on it pretty hard one night, parked it, then next morning it started running like this. It runs fine until it gets past 5-7 psi. Then it sounds like a machine gun, popping and stumbling. I’m just looking for any possible idea’s of what my problem might be… So far i’ve changed the intercooler, checked all vac lines, Got my friends to check all the vac lines, changed the spark plugs, and installed a new tt300zx fuel filter. still… nothing. up until then, the car diden’t give any warnings, or throw a CEL.

the car does have a walbro 255, besides the MBC the motor/ecu is stock, It’s still even using the stock side mount i/c lol. if anyone has any suggestions please post…

2

boost leak.

or possible MAF but my money is on a boost leak.

3

having the same problem…leaks at around 4500rpm. backfires a bit and gives a few huff’s, then quiets down. Any idea where the boost leak may be coming from?

Also happened to me when i hit 150, might have been the governor? but i had it removed from the first 240 the sr was in.

4

Hmm… My front mount arrived, i’ll get that in there along with all the new piping, and change all the vac lines… hopefully that works… if anyone has any more suggestions please post!, i need this thing running for the weekend cruise!

5

if you’re backfiring its probably because you’re either running pig rich,r misfiring or hitting fuel cut (which can also be from running really rich). first thing i would do is a boost leak test… 2nd check if any plugs are fouled.

6

if you bagged the car,

then parked it,

and it’s only oil cooled,

not oil+water cooled,

that’s your problem.

:roll:

uhh,… probably check your turbo,

I think you might have a boost leakage.

-1

7

crack in manifold would be my guess

8

hmmm… seems like everybody has covered mostly everything… I had the same problem and it turned out to be fuel pressure dropping when boost kicked in. check to make sure your spark plugs are gapped around 0.030" or even a little less… Most pregapped plugs are notorious for having huge gaps which end up getting blown out by the forced air.

9

double check your timing… its probably not the cause, but it doesnt hurt

10

+1 to that. If the belt slipped a tooth when you were caning the car it might slip another one day with more severe consequences.

Dan

11

+1 to that. If the belt slipped a tooth when you were caning the car it might slip another one day with more severe consequences.

Dan[/quote]

SR’s have a chain. I have never heard of a chain skipping a tooth tho. :butthead:

Also check your coilpack and make sure none have corrosion around it will be noticed at higher loads. Check your plug gap again.

12

could be more parts, i would thought first 2 check the MAF, after that check the filter of the fuel pump or maybe also fuel lines, if it isn’t i would check the coils