Looking For Insight To My Hesitation Problem

[Chris_RB]

Hello!

I have a 1992 GTS-t that I've imported from Japan, and this issue is starting to drive me nuts. I've tried a lot of different things from this forum, and others that I've found using search, but I still haven't figured it out yet.

My car hesitates...it's mostly present once the car is fully warmed up and has been driven a while. It mostly happens when accelerating, or going up a hill, or around a corner. It isn't a slight loss of power, it's like ALL power is GONE for 1-2 seconds. Sometimes it will even start to buck as power cuts in and out during that few seconds. I find it is typically OK when just cruising at a constant speed, but as soon as I come to a light, and accelerate, go around a corner, up a hill etc, it *occasionally* happens.

This is what I've done so far:

- fuel filter was tough to blow through, so I replaced it (this fixed the stalling issue I had)

- Replaced fuel pump with a SARD 265 l/m (tank appears quite clean)

- New coil harness

- coils appear to be in good shape

- new sparks

- new ignition module (this fixed a "different" hesitation I was also having)

- new Optima battery (will be redoing the ground once my terminals arrive)

- cleaned AAV valve (idled like poo and it was quite dirty) and set idle to 950ish. The solenoid still whines a bit though...

- tested different MAF, didn't change anything

I'm starting to run out of ideas...

I'm going to try a different CAS just to see...I will do that in the next few days...

I'm also thinking it may possibly be the fuel regulators?

Or EGR is messing up?

Would a buggy AAC solenoid be capable of causing this hesitation?

I'm really not sure anymore. I'm going to check for codes when I can find the time to get it tested. But I'm just wondering if someone has some fresh ideas, or a different perspective to help me out.

cheers

[axe s]

have you checked your fuel pump wiring... just a thought... might be cracked and earthing when you turn etc...

[Chris_RB]

have you checked your fuel pump wiring... just a thought... might be cracked and earthing when you turn etc...

The wiring in the trunk and to the pump appears to be in decent condition. Are there common areas where this would happen? I will double check to be certain though..but from what I saw when replacing my pump, everything was OK.

Thanks though!

This week I'm replacing the main ground with a 4gauge wire, and then a few other chassis and block grounds with 5-6 8gauge connections. I will also check other grounds to assess their condition as well...

Also, a friend of mine shorted out my battery and fried it (hence the new optima battery) when he was helping me jump the car. Fried my main 75amp fuse, and now my tail lights and dash lights are not working (all other interior and exterior lights are fine)...but all the other fuses appear to be ok? grr...that's all I needed with this other stuff...

I can figure that out later...I just want to fix this hesitation so I can take my car more than 10 KM's without it starting to jerk in a massive car-orgasmic kind of way...

[R334door(s2)]

did you get the pump rewired correctly something about r32's not having enough volts to run the pump properly so you get it rewired anyway this is where i would be looking hows ur coil packs u did not mention them.?

cheers

Allan

[r32woohoo]

get it on the dyno and try to recreate the hesitation and see what the results are

might make it easier to diagnose

what mods have you got?

check your Throttle position sensor (tps) voltage. its around 0.4v closed and 4v fully opened

check your ecu for any error codes

do you have any leaks in the intercooler piping? or anywhere else on the intake side for that matter

Try running some injector cleaner

is there any boost surge?

is it just a hesitation or does it miss as well when it does it?

What happens when you drop a gear and put your foot down?

[Chris_RB]

did you get the pump rewired correctly something about r32's not having enough volts to run the pump properly so you get it rewired anyway this is where i would be looking hows ur coil packs u did not mention them.?

cheers

Allan

Thanks Allan

Coil packs appear in good shape. I've tried another set and same thing.

Pump is rewired correctly. All the wiring appeared to be in good shape.

get it on the dyno and try to recreate the hesitation and see what the results are

might make it easier to diagnose

what mods have you got?

check your Throttle position sensor (tps) voltage. its around 0.4v closed and 4v fully opened

check your ecu for any error codes

do you have any leaks in the intercooler piping? or anywhere else on the intake side for that matter

Try running some injector cleaner

is there any boost surge?

is it just a hesitation or does it miss as well when it does it?

What happens when you drop a gear and put your foot down?

Thanks man. My last resort is taking it in to get checked. I wanted to try my own stuff first to try and save some cash. I had it into one shop and all they told me was one cylinder was a bit low on compression, but I do not believe low compression on just 1 cylinder would cause this issue.

TPS is good. It's been adjusted to 0.48v and then appears to be fine to fully open right around 4v.

I'm in the process of trying to find someone locally here that will check the error codes for me.

I will double check for leaks. I didn't see any previously.

I've ran cleaners

The car was overboosting. A new actuator helped, but it still gets to 1bar (as opposed to 1.2bar) on my apexi boost gauge. But on the stock gauge it doesn't read that high so I've skeptical on that 1 bar...I forgot to mention that.

The care is pretty much stock. I just have an apexi power intake, and now a SARD pump.

When I drop and gear and lay into it, there typically isn't any problems. It would be more likely to hesitate AFTER I lay my foot into it. If I give'er after a light, and then after I slow down, and then accelerate normal, it has hesitated then moreso.

And it just hesitates...its like all power is completely gone. Sometimes it comes back right away if I blip my foot on the gas, but sometimes it will also start convulsing (usually only after it's driven for a longer distance). So I don't really think it is 'missing' because its not like I loose a little bit of power, it's like the car is coasting in gear.

[infamous_t]

Bad AFM wiring? (wiring itself, not the AFM)

or dodgy knock sensors?

[Chris_RB]

I was wondering about the knock sensors myself...Would they cause this type of powerloss/hesitation if faulty?

I've inspected the AFM and everything seems to be in order...

I went through all my fuses this afternoon, and actually found more than just my tail light fuse was dead.

http://www.skylinegts.co.uk/R32-Fuses.htm

My shift lock fuse was also burnt - what the heck does this do?

[r32woohoo]

you can check the error codes yourself

http://www.skylinesaustralia.com/forums/EC....html&st=20

Do that and look for the flashing light on your dash. Long flash = first number, short flash = second number eg: - - - . . . = 33 if that makes sense

ECU Diagnostic Codes

11 Crankshaft position sensor

12 MAF sensor circuit (air flow meter)

13 Coolant temperature circuit

14 Vehicle speed sensor circuit

21 Ignition circuit

31 ECU (ouch!)

34 Knock sensor

43 Throttle position circuit

45 Injector leak

51 Ignition circuit

54 Auto signal to ECU

55 All OK

Turn the ignition off to put the ECU back to normal.

Edited June 3, 2008 by r32woohoo

[Chris_RB]

Thanks for the link man.

Here is some pictures if anyone searches and finds this thread for future reference...

http://www.skylinesaustralia.com/forums/in...t&p=3723574

I'm going to go out and try this when it stops raining...

That would be brilliant if it's something came up that I haven't checked yet...

I really need this car working because I start a new job in emerg (I'm a nurse) so it is going to be a real buggar to take the bus...a 30 minute trip becomes 1.5 hours...

[Chris_RB]

Ok, wow, should have known about this a while ago...

I'm getting a few errors.

12 MAF sensor circuit (air flow meter)

34 Knock sensor

54 Auto signal to ECU

I do have a custom ECU so I'm not sure if 54 is relevant? But the other 2 would make sense.

[Chris_RB]

can't seem to edit my posts...sorry for double posting so much,

But the #54 I have confirmed is a normal code for this ECU...

Anywhoo, I will order a knock sensor, and take a closer look at my MAF and go from there...

Are they easy to replace?

[Chris_RB]

yet another afterthought here...

The hesitation seems to be worse when it is a rainy day. So maybe the MAF is indeed fooked. a little moisture in the air, and it starts to hesitate much sooner than if it was a normal sunny day. I can go about 2km's to get groceries just fine with maybe one or two very short hesitations coming home, but when it's rainy outside, I can't even make it to the store without having quite larger and longer hesitations where there is no power...and it's mostly right after I stop at a light so it takes a very fast car, a very LONG time to get up to speed because my car is having a mini orgasm while I'm trying to accelerate.

I was thinking before that maybe my fuel regulator wasn't regulating well, but I think I would still have SOME power there, instead of an all out CUT in power. So I'm moving away from that idea...

I'm pretty sure I don't hear any knocking. But who knows, maybe my low cylinder could cause a knock sensor to wig out? OR, it's just a faulty knock sensor, and when it wigs out, it cuts power to my car for a brief time?

I have a friend with a different MAF that I'm going to borrow. The ECU should be reset now after the diagnostic mode was shut off, so I'm curious to see if that will come back...then it would be the wiring and I can take some volt readings at the ECU to see if my wiring is bad. I will also inspect the plugs.

Any thoughts/opinions/ideas would be appreciated. This is my first RB and so far it's been a royal pain in the ass, but I do have a basic understanding of how it all works... Thanks for the help thus far~!

[r32woohoo]

They do tend to become a major pain in the ass but it makes it all the more enjoyable when you fix it

But anyway, I dunno about the knock sensor but the afm error makes sense.

You might just have a loose connection in the afm, theres a diy thread on how to re-solder the joints, try that.

[Crans]

I would say MAF straight away. Mine used it loose all power randomly(as in felt like engine turned off) could be for 1.2 a second or for 3.

Replaced MAF and all good

[Chris_RB]

I would say MAF straight away. Mine used it loose all power randomly(as in felt like engine turned off) could be for 1.2 a second or for 3.

Replaced MAF and all good

Dude, you have no idea how happy I would be if that was it. I tried this earlier, but there were other problems with my ignition system causing a different sort of hesitation...so I probably overlooked this issue.

I have a buddy with a spare MAF, I'll give it a go tomorrow after I inspect the condition of the soldering done to my current MAF.

[Chris_RB]

I feel like a real dummy because I knew the MAF was a common problem in these cars, but I had tested the other one before, and I was still having problems, but as I mentioned, that was from something else (ignition module) and now after resoldering the MAF I went out for 30 minutes and didn't experience the nasty hesitation. I will pray that fixed it...but I wont be sure until a few days...

Should I also replace my knock sensor if the ECU was pulling that code? Maybe it would help my mileage if it is bad...

I will drive more later in the day...

I was also wondering if a bad MAF would also cause the engine to detonate...bad air/fuel ratio causes it to get too hot, and detonate? Just curious...because I had some earlier. Sounded like crunching tin foil under water...but I didn't hear it now when I would be in full boost, approaching the redline (when I would hear it before)..

Edited June 4, 2008 by Chris_RB

[nizmonut]

its always the tps.

[Chris_RB]

its always the tps.

TPS? That was one of the first things I checked. Set it to .48ish and then it is quite an even climb to 4v fully open.

I drove the car quite a lot tonight without a problem. Also, after cleaning the AAC valve the other day, the idle is PINNED at 1K (I set it a bit higher because I like it better than even 900-950). It used to jump all over, and stall out too (which I think resoldering the MAF took care of).

I will pull codes again in a few days to see if the knock sensor is still coding.

But I got on a highway tonight, and FINALLY I can feel nice pull right up to 180+ without any problems. I can also stop at a light without fearing if I'll make it through the intersection...lol...this is what I bought the skyline for - to enjoy my driving experience and that just started tonight...