High RPM Hesitation/Fuel Cut and Glowing exhaust manifold!!!!!

[love_boost]

until you get a wideband you can pull the plugs and check.
if they are ghost white your running lean, which im sure you are already, if you havent changed it already change the fuel filter. fuel pumps are known to gum up with crapfrom over the years or bad gas, it happen to my friends low km silvia already.

[BrianV8]

Now that i think of it could be that POS fuel pump regulator box in the trunk. Try to rule this out man. There is a box in the trunk that regulates how much power the fuel pump gets. It cranks the fuel pump up at high rpm,s and slows it down at idle. Unit usually gets stuck on idle mode which makes sence for u running lean and heating up a header when you on the gas. Going about this procedure its an automatic quick way of giving it a proper 12volt constant. Everyone who owns a skyline should do this!!!!!

1. Go into your trunk and remove the driver side panel. If you follow the harness you see you'll see on part go in between the inner and outer fender. Reach in there with your hand you'll feel a little box.

2. You will see two nuts holding that box in. Remove the nuts and pull out the box.

3. Unplug that box and throw it in a fire.

4. Take the big white wire and the harness you just unplugged. Cut it and ground it.

You have now given your fuel pump a 12 volt constant, and no fuel pump issues ever again!!!

[pmurr181]

I have looked at the first three spark plugs and they seem normal to me they are platinum plugs and they are pre gaped to 0.8 i believe. I have changed the fuel filter. If its my fuel pump how would i know? And BiranV8 i am going to try your suggestion today. thanks.

Oh and the knob on the AFC is all cracked and chipped from old age. Is there a way that i can tell where the old position should be? Or could i Simply Remove the AFC and everything would go back to stock fuel/ air maps?

[pmurr181]

I need to know if i remove the AFC if it will cause problems, cuse i moved the knob and i have no way of knowing if i am too rich or too lean. EEKKKKKK does anybody know about this crap lol. And if my exhaust manifold is getting so fffing hot does this mean i cooked my o2 sensors?

[BrianV8]

do what i told you with remove that reistor box and giving your fuel pump 12v then get yourself a wideband.

[mcfly]

check your timing

[Skym]

AFC (Air Flow Convertor) should play with load sensor (MAF) signal. It basically makes ECU switch to high load cells for rich and low load cells for lean A/F ratio and similar with ignition map. AFC is designed to be used with intake, exhaust mods. Shouldn't be used for anything else. Get auto sparky or someone experienced with wiring to remove it and tune stock ECU properly with Nistune for stock ECU.

AFC might have made ECU stay on low load cells on stock fuel, ignition maps. Checking with Nistune tuning software on dyno will confirm this, as cursor will stay on low load cells.

Talk to Ztune for Nistune -

http://www.ztune.ca/

It does explain the fuelcut, as stock ECU has a load limit fuelcut, which engages when MAF maxes out due to overboost or excedes the set settings on ECU at factory for some reason. AFC could be making ECU hit those load limits earlier than it should.

[pmurr181]

How do i check the timming?

Where is ztune located?

[Skym]

You need a timing light -

http://toolmonger.com/2008/02/11/cheap-ass-tools-xenon-timing-light/

Connect timing light to battery. Then there should be a black loop of wire on intake side of ignition module (near coilpack loom plug that plugs into ignition module), which is located on top of back of engine. Connect timing light to that loop of black wire and aim timing light at crank pully. You should see a orange mark (0 degrees) and multiple white marks, which are 5 degrees apart.

CAS timing info should be on white sticker at top right of underside of hood. I think 15 degrees BTDC (Before Top Dead Centre or before piston reaches top of cylinder and stops moving) is manual trans and 20 degrees BTDC is auto trans.

If you need to adjust base ignition timing, CAS is located on front of exhaust cam. Turn off engine, undo 3x nuts so CAS can be rotated. Turn engine on and aim timing light at crank. Turn CAS until you get correct base ignition timing. Once set, turn engine off and tighten 3x nuts. ECU can adjust base ignition timing up, down 4-5 degrees, so might be frustrating to set. That's the idle stabilisation feature on stock ECU doing that.

Click on "contact us" in top right in link I posted above.

Or to save you clicking on "contact us", here's the link -

http://www.ztune.ca/contact.aspx

[pmurr181]

thank you very much. i will be either contacting z tune or trying some stuff my self before hand.

Oh the other day i took my spark plugs out and they were not fouled or white. However it is still making the fuel cut and hesitation at high rpms and heating up the exhaust manifold. However if i take it all the way up to redline at in every gear when its COLD nothign happens. i am only getting the fuel cut/hesitation at high rpms when the car is hot? And its not a small noticeable thing its is very drastic and shakes the car. Could this be timming, but not fouling the plugs or running to lean?

thanks for the help agian

[Skym]

I've noticed running lean = higher exhaust temps and higher engine temps.

Engine ECU runs engine richer (runs on warmup fuel, warmup ignition timing tables) when cold. That makes me think the AFC is the cause when engine is warm.

Running too lean could engage safety fuel cut at 5100rpm if engine knocks and engine ECU detects this via knock sensor, but can't confirm this.

There's more than one fuelcut on stock ECU, so it could be the MAF load limit fuelcut or safety fuelcut. The rpm fuelcut kicks in should give away safety fuelcut.

[pmurr181]

ahhh that makes a lot more sense. i am going to go put an OBD1 scan tool on it and see whats up with it. thanks agian for the info.

[mcfly]

ahhh that makes a lot more sense. i am going to go put an OBD1 scan tool on it and see whats up with it. thanks agian for the info.

haha good luck

[pmurr181]

the scan tool wont tell me anything?

[Skym]

Scan tool is for checking error codes, etc. As far as I know with Nissan's hand held consult diagnostic tool, can see knock levels. Nissan checked my car for knock, before I bought Nistune.

Nistune tuning software can download maps, tables, etc and display what the ECU is looking at in realtime on the maps, tables. Never checked the knock count window while running car without Nistune installed, but it might work.