My S13 has flat spot and backfires

troopiec · Post by **troopiec** » Fri Jan 20, 2012 11:31 am

Hi guys, like i said in another thread my car really struggles when it is cold, even to pull away at 1500rpm it stutters and feels like its missing, once it has warmed up to normal temperature it drives very nicely but occasionally there will be a bit of a flat spot just before boost and when boost kicks in she will fly, also if im coming off the freeway and i just take my foot off the gas and stay in the current gear, as the engine revs slowly drop i sometimes will get a few fairly loud backfires at around 2800rpm but this does not always happen.

I have fully serviced my car yesterday, diff oil, gearbox oil, engine oil, fuel filter, oil filter, and spark plugs (bcpr6es-11 gapped to 0.8mm) It still does the same thing, the car drives nicely and i hope this is not a huge problem as its just a bit irritating.

Could it be bad coils? ive checked my spark plugs numerous times and they all nice and dry and look fine and all my coils and plugs are connected correctly, i also noticed that it looks like my cam angle sensor has been rotated a bit as there is a sticker on the cam cover and a sticker on the angle sensor but they do not align (not sure if that would make any difference)

Oh also i must add that my idle isnt great, if i leave it for long she will idle at about 750rpm, but if i rev it to about 2000rpm then itl idle at about 1500rpm for a while before it slowly drops to 750rpm.

Could it also be a bad air flow meter? I remember my friend having similar problems with his nissan almera because his airflow meter was messed up. Plus i also have a 76mm complete free flow exhaust without any silencers, just a f1-x 100mm tail box, perhaps its too free for the stock turbo?

My plans were to take it to Dynotec and get a uniq chip fitted and let him just tune it for feuling but i'd feel better knowing everything is 100% before i let anyone Dyno it.

I always say - Maintanance over Modification

So what do you guys think?

rat · Post by **rat** » Fri Jan 20, 2012 2:52 pm

1 clean afm
2 check for boost leak
3 timing set to 15deg
4 exhaust wont do that
5 try not make more then 1 thread about the same thing

aep886 · Post by **aep886** » Fri Jan 20, 2012 4:08 pm

try not make more then 1 thread about the same thing +1

troopiec · Post by **troopiec** » Fri Jan 20, 2012 4:49 pm

Sorry didnt mean to make more than the one thread, this thread was aimed only at the back fire which was new but thought i would mention the previous issues, but thanks for the advice, what do you guys use to clean the afm? because my friend and i have already messed up 2 almera AFM's, the first we cleaned with carb cleaner and the car would not start again and the engine error light came on, we had to replace the afm, then later on when that one started giving trouble we cleaned it with very expensive electrical cleaner and it again messed up completely, so im not very keen on cleaning mine yet lol

rat · Post by **rat** » Fri Jan 20, 2012 5:18 pm

I normally use carb cleaner.

troopiec · Post by **troopiec** » Fri Jan 20, 2012 11:59 pm

Well i learnt something very interesting tonight thanks to Daniels post in another thread.

He posted steps on how to check the ECCS for errors, i did everything correctly and with the ignition on and the car not running it tells me 55 that everything is ok, but with the car running it gives me 3 red flashes and 4 green flashes over and over again, and according to his list it says its my knock sensor, so i looked for my knock sensor like the pic on the other thread i found mine in the same place however there is no wire coming out of it atall, its just bolted in there without anything connected to it.

So what should i do? i see there are 3 loose wires laying around in that area, obviously the previous owner that did the engine swap didnt re-connnect everything.

Could the knock sensor be causing some of my problems?

troopiec · Post by **troopiec** » Sat Jan 21, 2012 12:50 pm

Great news! i Reconnected my knock sensor with the right cable and clip and now my error has dissapeared, with the engine running it repeats 55 over and over so thats good news. I must still drive it but at idle the throttle response has greatly improved so hopefully thats fixed my problems

araf69 · Post by **araf69** » Sun Jan 29, 2012 2:05 pm

Also check fuel pump. I had same problem, backfiring when going into boost

*Nissan 200SX Club - South Africa