Rb20Det Hard To Cold Start And Stalling Out When Warm When Returning To Idle

[Benno31]

I am hoping someone can shed some light on this problem.

RB20DET in S13.

Cold start, it is shocking. I have to use the throttle to get the car to start like it is some crappy old carby fed car from the 70's. Even with throttle it takes a few goes to get it to run.

When warm the car sometimes stalls out when returning to idle as I pull up at lights/stop sign/etc.

The engine is stock with the only mods being a FMIC, 3" exhaust with high flow CAT and a pod filter. ECU is a Blitz remapped factory item. Cold start has always been an issue but is now worse then ever. Stalling out when returning to idle was initially a problem but was solved by running a better earth to the GTR in-tank fuel pump. Over the last 12 months it has got worse.

The engine was recently treated to some fresh oil, new plugs, new pod filter and the AFM was cleaned. Fuel filter is only 12 months old.

As a side note, I do believe the alternator to be suspect, when turning headlights on at idle the car almost stalls initially and is more prone to stalling out when returning to idle.

Coilpacks were tested 2 weeks ago and were performing well. Injectors and fuel reg are both 22 year old factory items.

Suggestions welcomed.

Cheers,

Ben.

[Bsa]

I have the same problem on my rb20 and I was suggested to clean the acc valve with carby cleaner also I did my own research and my tps is the problem on mine I'm only saying what iv been told and figured out on my own I'm not I pro but could still work

[Benno31]

Thank you for the feedback. I have always been sus on the TPS. I will give the AAC a clean and failing that I will try another TPS

[Bsa]

I feel your pain mate iv been replacing every gasket and sensor on my car for the last 6 months oh well the joys of having a import

[Benno31]

I feel your pain mate iv been replacing every gasket and sensor on my car for the last 6 months oh well the joys of having a import

the pain is all worthwhile though. Just after I dust a $60k + HSV etc with my $10k import I suddenly feel better.

[BOOZTJUNKEY]

Do u run an after market bov?

[Benno31]

No, factory BOV, fuel rail, fuel reg, injectors and all other associated piping with the exception of the intercooler piping. All of the emission piping is still there and there are no noticeable vacuum leaks.

[Bsa]

I have the exact same problem and going off my ecu it's saying the tps is the problem. Try pulling off your passenger kick panel then pull the ecu off you will c a screw with a light next to it turn on your reds and then turn the screw fully anti clockwise and the light will flash if you get 55 which is 5 long flashes and 5 short flashes. The code it's giving me is 4 long flashes and 3 short flashes if you have that it's the tps there is a forum that gives all the codes and meanings. You can also read it on the dash do that and it may just be your problem

[Bsa]

Forgot to add 55 is all good

[Benno31]

Thanks Bsa. I will try that tomorrow. Thankfully my ECU is custom mounted and I have no interior so accessing it is easy

[kitto]

The cold start issue sounds the starter motor cranking signal wire was not wired in when the conversion was done. Common error.

It tells the ecu to dump more fuel in when starting. Without this. The engine is a prick to start.

The hot issue could be anything. Tps, aac valve, stuck open iac valve etc.

[Benno31]

Thanks kitto, I will double check starter motor cranking wire.

[blind_elk]

Have you thought about getting the injectors cleaned?

Have you tested the fuel pressure?

What's the base ignition timing?

Edited September 9, 2011 by blind_elk

[Benno31]

Have you thought about getting the injectors cleaned?

Have you tested the fuel pressure?

What's the base ignition timing?

I am going to investigate cleaning the injectors. Fuel pressure is good to the filter, I haven't tested after the reg yet but will do tomorrow. I think I may have spotted a leak from one of the fuel lines where it connects to the filter. Either the hose has a small split or the filter has a crack.

Ignition timing is factory.

kitto: starter motor cranking signal wire is connected and working.

[kitto]

kitto: starter motor cranking signal wire is connected and working.

Interesting. Have you looked at things like a shitty AFM? Tried cleaning it with contact cleaner? Clogged injectors, shitty FPR could be an issue, but i feel the problem lies elsewhere. What is the ignitor pack like? Working properly? Same with the coils?

What plugs are you running? I know a lot of people love to run Iridiums thinking they are a better plug, but this is not always the case, they are designed to last a long time, not necessarily perform. A set of NGK BCPR6ES gapped to .8mm is ideal!

As said, could be TPS switch, possibly even a faulty a ECU engine temperature sender. There's quite a few things that could cause such an issue.

Have you checked the IAC valve? Hard to get to i know, as it sits under the inlet plenum, but these commonly freeze open or closed. Causing all sorts of idle issues.

Its a process of elimination really.

[Benno31]

Hey Kitto,

AFM is cleaned, FPR could be an issue, still have to do further testing on that. I do somehow suspect that either the GTR in-tank pump may be on the way out or I have an alternator issue as I can hear the pump noise fluctuating a fair bit even at idle. I have a theory that perhaps the voltage to the pump is inconsistent and could be causing the fuel pressure to fluctuate.

I have bench tested all the coilpacks 2 weeks ago and they came up perfect, better then a new set of JJR's in fact.

I am running BCPR6ES gapped to .8mm and they are only 2 weeks old, changing plugs didn't make a difference.

I haven't checked IAC as yet. Might not be able to check it until next weekend now.

Is the ECU engine temperature sender the same thing as the coolant temp sensor?

[kitto]

Ok, have you got factory wiring running to the fuel pump? It may be suffering voltage drop.

I would suspect a faulty fuel pump/wiring before a factory fpr. Ive never had an issue with the stock fuel pump.

How is the pump wired? Is the ecu still controlling it via variable voltage? Or is the ecu switching a relay to give a constabt 12V to the pump?

[kitto]

That was meant to be: ive never had an isue with the stock fpr* not fuel pump

[kitto]

Also, the engine temp sender is different to the gauge sender.

Its right next to the gauge sender, yellow plug on both the harness and sender. Two wires. Right near the fpr.

[Benno31]

Ok, have you got factory wiring running to the fuel pump? It may be suffering voltage drop.

I would suspect a faulty fuel pump/wiring before a factory fpr. Ive never had an issue with the stock fuel pump.

How is the pump wired? Is the ecu still controlling it via variable voltage? Or is the ecu switching a relay to give a constant 12V to the pump?

Currently using the factory wiring for the fuel pump. I did run an extra earth though. I am suspecting voltage drop. I might jerry-rig a relay for fuel pump power and see if it makes a difference.