Another Rb20 Problem Thread

[daisu]

Hey people, I know these threads pop up quite often and I've read through all(if not most) of them looking for things to check.

This issue I'm having is the engine hits a flat spot of hesitation while trying to accelerate, it happens around the 2-3krpm mark and can sometimes push through it if I pump the throttle up and down, otherwise it'll get stuck and not accelerate (kind of like a limiter) and the car gets jerky.

It also does the hesitation thing while trying to cruise.

Once you get past about 3krpm it runs fine and there is no issues with power at all, it will rev right out to limiter with full power, (not that I drive it that hard anyway).

Also, if you've saw me on the QR skidpan on the 2nd you would have noticed how badly the car was suffering from lack of power down low.

It has been doing it pretty much since I got the engine (from a halfcut) used to only do it rarely, but has been increasing in frequency and now it's doing it all the time. Doesn't matter if it's cold or hot.

It also used to have intermittent idle issues but I traced that back to dirty AAC valve (which I've cleaned now and idle is good).

Modifications, not many (if any, lol) has a no name dump/front/straight through, pod filter and front mount. Not running any sort of boost controller but it runs about 11psi by itself (has done since I got the engine out of the halfcut). Otherwise its stock.

Things I've checked so far include,

fuel pump - getting healthy 13volts on idle

coilpacks - I can't see any evidence of cracks or burn marks, but they possibly could be failing? I cleaned out the little cylinders that the springs sit in and also stretched the springs a bit to make sure they were contacting the spark plugs properly, and cleaned the tip of the carbon pieces.

sparkplugs - brand new copper plugs gapped to 0.8mm (maybe a little closer to 0.7 as I was worried about coilpacks not having enough energy to spark the gap).

AFM - cleaned with contact cleaner, opened the cover and checked the solder joins, they were good but I resoldered them anyway

ECU fault codes - 55 all good

CAS/static timing - checked with timing light, have tried on 15BTDC(factory) and a bit advanced (20BTDC) no affect on hesitation

TPS - was on .4V when I checked it so I set it to .5V

checked plugs were all inserted properly.

Things I haven't checked or am thinking of,

fuel pressure - can I just put a gauge inline between the fuel filter and the fuel rail

injectors - possibly they are clogged? do I have to get them flow tested to find out?

fuel filter - I haven't changed for a while, but I'm thinking if it was this the problems would continue higher in the rev range, its cheap and easy to rule out though

inlet piping - i can't see anything obvious, but maybe it is leaking, I checked all the hoses/clamps. I'm thinking to leak test the pipes I'd need a cup on one end and a cup with gauge and fitting to pressurize it.

Thats pretty much all I can think of at the moment, If there is anything else you can recommend that I check I'd be happy to hear it.

Thanks, Luke

[Lock_to_lock]

My car does the same thing before 3k. It feels like when taking off, like there is nothing there. So i back off a put my foot down again and bang, she starts to go. almost like a light switch.

[bubba]

*could* be the temp sensor for the ecu, the symptoms sound like when my old RB20 was running in cold start.

[shepo]

mine used to do the same thing, it was the coil packs. the best way to tell is you have the car idling, and you disconect them one at a time until when you disconect one of them there is no change to the idle.

sounds confusing but it worked for me.

does yours have a rough idle?

[TTT]

mine used to do the same thing, it was the coil packs. the best way to tell is you have the car idling, and you disconect them one at a time until when you disconect one of them there is no change to the idle.

sounds confusing but it worked for me.

does yours have a rough idle?

If he was having the same issue you described, it would already be idling like an EJ20 to start with

[Lock_to_lock]

well my idle is fine. Buut another problem i have is i have to give the car gas to get it to start...like a non EFI car. It primes fine. So not sure what is going on there.

With the temp sensor for the ecu, is that the the one next to the temp sender for the temp gauge on the dash?

[TTT]

LOCK-TO-LOCK - speak to user CUBES.

It can be "tuned" out that problem.

he managed to sort it out on his PFC a while ago.

there may be other ways around it.

I can't quite remember how he did it now or what he had to change.

[Lock_to_lock]

Thanks for your help mate, ill send him a pm

[dmr]

well my idle is fine. Buut another problem i have is i have to give the car gas to get it to start...like a non EFI car. It primes fine. So not sure what is going on there.

yeah mine's the same. so is a couple friends rb20's. never gotten around to resolving the problem. i noticed it started doing it when i changed oils but i know that's only coincidental.

[bubba]

Pretty sure the ecu temp sensor is the yellow one. I originally snapped mine when putting the 30 in and used the 25DE sensor (brown) to get it running. Ran in cold start all the time till I grabbed one off my mates RB26 manifold.

Edited November 15, 2007 by bubba

[Lock_to_lock]

ah k, i know the one your talking about...

It seems fine to me, could i have the wrong one? Iv been told there is two different types.

EDIT: Sorry about jacking the thread. Another thing. The car randomly runs really rich, to the point where the cabin get fumed out. I know nothing about the cold start mode. But could it be going into this mode?

Edited November 16, 2007 by Lock_to_lock

[Lock_to_lock]

Anyone?