issue.... heelp asap

[h4X6]

hey

got my car back finally and been working to get it back to someone decent condition

issue is car takes bit of turning over to finally start... its like there isnt any fuel getting to it, then all of a sudden it will fire up

second... once its started it will idel at 1500ish rpm, then go down to 800ish and then just die out... wont rev past 3000rpm, just cuts out

that i have done thus far today, installed new plugs, oil change, removed IC piping to do plug change, had to remove maf due to new air filter install...

thinking its the maf... any thoughts on if that is the case or anything else you think it might be...

it was running completely fine (other then the rough starting) before i did the above... so it could be sparks? could it be maf?

thanks in advance guys!

[gtrjon]

sounds like a maf. either swap one out with a known working one or clean it and resodder.

[Skym]

MAF is easy to check, just unplug MAF and start engine. Stock ECU can run without MAF, but rev limit's to 2500rpm or so and I think uses a preset value for MAF input. Stock ECU only feature.

If knocked TPS plug when changing sparkplugs it can damage the TPS and if wiggle TPS plug, engine can stall (what happened to my car) due to flooding engine with fuel.

If hard start when cold, hot, cuts out, check ECU for CAS error code. Could be a loose plug.

[h4X6]

Loose plug as in spark plug or a diffetent plug?


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[Skym]

I meant CAS plug. But check the other plugs, grounds (especially on ignition module), ignition fuse (lack of ground on ignition module can blow this fuse) to rule them out as a cause.

Hard starting points towards CAS and get CAS error code on ECU. If bearings x 2 inside CAS get worse, engine randomly stalls when on motorway, etc.

Also you'll get MAF error code on ECU if unplug MAF and start engine, so that will need to be cleared.

[h4X6]

How do you clear and check for codes? Never don't that before.



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[Skym]

To check, clear error codes on stock ECU, Nissan's Consult (handheld diagnostic computer) at Nissan dealership, Nistune tuning software + Consult cable, Conzult software + Consult cable.

I gather can clear error codes via pulling negative cable on battery and pressing brake pedal to remove any left over charge, refitting negative cable. But note that the stock radio, clock, etc probably will be reset.

[h4X6]

Well then looks like I won't be checking ecu codes lol. No consult or anything like that.


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[Bee-RSkyline]

I had issues similar to this a while back. Turned out to be my TPS, it had been bumped or something and wasn't correctly recognizing idle. Also caused the car to jerk on low throttle.

[h4X6]

ok i am thinking it my tps as this point... its not the maf, thats completely fine

car starts perfectly now, no issues... (thinking it was bad gas since it had been sitting a couple years)

however now when it is started, my idle sits at around 1800rpm, i refuses to go down any lower...

suggestions? can one fix a tps or does one need a new 1?

thanks guys... almost drivable....

[SlidingSideways]

I don't know what car u have but this works on my car for checking codes

http://www.skylinesaustralia.com/forums/topic/266512-reading-nissan-fault-codes-ecu-fault-codes-how-read-them/

-stayin' alive with code '55'

[h4X6]

thanks sliding! thats helpful!

anyone got any ideas what going on based off my description at all?

thanks!

[Skym]

With that way, you have to make sure screw is set back to run properly, or cat light on dash (acts as engine check light that can flash error codes) can flash when hitting bumps in road. I use Nistune, as it's less hassle that way (don't have pull off kick plate in bottom of doorway, interior panels, unbolt and pull out ECU, which could pull loom out of plug if pulled on).

ECU and AACV should be set at same rpm (650rpm). If idle rpm is higher, AACV screw is probably set incorrectly. It would require pulling stock ECU out, note position of screw (side of ECU) on piece of paper and amount of turns when turning screw and turn screw all the way to left to enter idle rpm adjustment mode. Then unplug AACV (to stop ECU adjusting idle rpm) and adjust idle rpm to 650rpm. You would need Consult to do this properly, as can see accurate rpm readout. Then plug AACV plug back in and see if idle stays the same. If not, repeat upplugging AACV and adjust AACV screw until it's at correct idle rpm. Then adjust screw on side of ECU back to position it was before (run mode). Also, be aware that adjusting screw initially back towards the right might raise idle rpm.

But make sure TPS is set correctly first (multimeter on TPS plug) -

http://homepages.vodafone.co.nz/~lakewood/Skyline/ThrottleTPS.htm

[h4X6]

Which one is the aacv? I know where the TPS is... is the aacv the one on the back of the intake? Near the firewall?


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[Skym]

I think you have to set screw back to run position with AACV unplugged (so ECU doesn't raise idle rpm).

On firewall side of top part of intake plenum. There's a hose (just before throttle body) on side of intake pipe (intake pipe that goes over top of engine), which goes to IACV (from T fitting off this hose to IACV on top of bottom half of intake plenum), then AACV (located on side of intake plenum, facing firewall).