95 R33 Gtr Slight Miss At Idle And Cold Drive Issue

[JB4U]

Hey guys,

I need some help.

I have a 95 r33 gtr, basically standard (only mods are yellow jackets, full turbo back exhaust with no cat, and k&n panel filter). The timing belt was changed with a full kit 6k ago and the other filters, oil and and plugs changed every 5k.

Now I have two issues,

1, not all the time but every now and then it has a slight miss at idle, not enough to affect the tacho but enough to hear and feel engine miss. Tends more to be when engines hot. Only at idle though, can smash it through rpm without issue.

The fuel pump is noisy and if I turn the car to on but not start it, let it sit for abit after priming, and then go to start it cranks cranks stutters and then starts. as if fuel pressure leaves after primed. But if I go to on and then start straight up it doesnt have an issue.

2, in the morning I start it without issue. Idles fine with no miss or anything. When I go to drive off at about 2-3k rpm it splatters, misses, resists and carries on. Then after about 100metres up the road it clears up and drives without any issue. What could be stuffed. Note is issues isnt as bad in the arvo after work (8hour shift).

If you can help that would be fantastic!

[JB4U]

Please help!!!!!!!

[RBrennan25]

Are the spark plugs gapped correctly? That would be my first though for the rough idle/misfire.

As for the fuel pump, they do wear out after a while and need to be replaced. Is it standard or aftermarket?

[JB4U]

Im using BCPR7ES spark plugs and been told thats right but ill have a look.

Yeah its stock so I might go get a bosch 040 and put that in it, dare say the standard ones on its final legs.

Any idea about the missing, resisting, and carryonh on when told issue? I thought maybe cold start valve but it wouldnt idle roght if it was that.

[RBrennan25]

Just checked they're gapped right. They should be .8 according to Nissan.

As far as the fuel pump Bosch pumps tend to be a bit louder, have a look at the walbro pumps.

Also the plugs could cause that resistance/hesitation because they aren't igniting the vapour. Exactly what happened to my car so I checked and the muppet who owned the car in Japan had gapped them to 1.1. Couldn't even hit 5 psi boost without a massive misfire.

[RBrennan25]

To be perfectly honest though if the fuel pump and spark plugs are both bad and you fix them you'll probably find your hesitation issue is caused by them and will go away once they're fixed

[JB4U]

So my plugs should be alright?

But the current fuel pump is pretty loud, especially on priming. Ill get a new pump and chuck that in, see what it does. If it doesnt fix it reckon maybe a faulty AFM?

[JB4U]

Or maybe even a faulty knock sensor?

[JB4U]

Also I live in darwin and the weather is rediculous hot and humid at the moment. Could that have a noticeable affect?

[scotty nm35]

Sounds to me like one of your afm's has a dry solder joint. There is a 'how to' on fixing it around somewhere if you have a search around. Unless you can borrow someone's afm's for a minute or two?

[JB4U]

Yeah I was thinking something afm related. Ill see if I can get an afm off a mate or something to test. Will also have a look for that thread.

[JB4U]

Off the top of your hear are there any afms off similar cars that would work on gtr? Just there are not very many 33 gtrs in darwin

[JB4U]

Also the slight idle miss happens only sometimes, and generally when the cars hotter. If that helps with diagnosis?

[GTRPSI]

Everything points to cleaning your air flow meters firstly and if that fails check for dry solder joints.

About the comment of you not being able to hit 5psi with 1.1mm gaped plugs sounds like another issue, possibly your ignitor or a ground issue or even the coils are not insulated properly or breaking down, sure .8 sounds right if your running around the 21 psi plus mark but you should be able to run it to 1 bar with 1.1 without a issue, its over that boost that and you start closing the gaps down a bit if you hit missfire on boost and only if needed.....

Edited November 18, 2013 by GTRPSI