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Problematic Rb25det

Benzino33
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Benzino33 Experienced

Benzino33

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Posted (edited)

Ok, where to begin?&

I bought my r33 turbo last June and had a few problems with it. The car ran fine at first but had an idle problem and would stall in neutral when coming to a stop. Found out it was blow-by and a dodgy stepper motor. Fixed that,moved on. Was alright till the end of the yeah when I got a knocking noise when applying throttle, took it to the mechs but they thought it was lifers, in the end, we found the car had done a bearing and i decided to rebiuild.(done at CW) Rebuild gave me a forged long motor, but all the other parts of the engine were put back on. When I got it back, ran ok but not as good as I expected, then the engine started to misfire at idle and about 5000rpms. Fast forward 2 weeks, changed the coil packs and spark plugs(platinum). It seemed to fix everything nd the car ran perfect for about a week, then misfire returned, changed the coil packs again (under warranty) and changed the spark plugs to re-gapped ones (0.6mm). This was done when I took it for a dyno run and we found that the car ran extemely rich (it was off the charts), it would break down at high revs so we changed the plugs to the gapped ones. It didnt make much power on the run but the guy said he couldnt tune it coz it was a stock computer and would require a costly remap, or for a few 100 bucks more I could get a power-fc and that would fix it.

I didnt know too much about the car's history but knew it used to have a fmic,very lound and annoying aftermarket fuel pump, hi-flowed turbo and a pod filter. I have the feeling that the ecu would have probably been re mapped, but obviously didnt turn out too well. When I was at the dyno, the guy told me the car did have previous boost modifications but there were some underlying things he could diagnose off that ecu.

Also, a few days ago, I was driving and the car suddenly shut down, I knew the fueal pump had gone. I had bought a spare one months earlier luckily(Walbro). Chnaged it the next day and it ran alright but I'd find that at cold start it would hesitate when I'd go to third gear, also when I put it in neautral coming to a stop, it seems to hunt a bit to find the right idle.<br />Ok here's a run down of how its running today:

Seems to have lost a lot of power

Hesitates

Loses power up high

Runs rich

A lot of it is hard to explain but it's just not running right. I did change a few more parts over the course of owning the car. These include O2 sensor, Throttle body, TPS, coil packs and spark plugs.

Now I have decided that it just might be a faulty ecu, I'm looking to but one from here on the forum (an already tuned one).

What I would like to know is:

Will changing the ecu completely change how the car runs and fix the problems?

Am I better off just getting another series 1 stock ecu?

I feel like I've done as many physical mods to help fix this as I could

Sorry for the long essay, but I really do need to know what is going on with the car, I would really appreciate and input from any other Skyline owners. Has anyone else come across prblems like this?

Hope to hear from you guys real soon, fel free to ask any more questions. Thanks

Ben.

Edited by Benzino33
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https://www.sau.com.au/forums/topic/265207-problematic-rb25det/
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eeiko321 Experienced

eeiko321

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Posted

ok...

just trying to understand things a bit more....

its really hard to say without seeing your vehicle...

but from the sounds of things, id definately piss the mechanic off. shoulda pulled the plug from his first f**k up.

take it to someone more reputable and knows what they are doing.

im sure people can give you pointers as to where depending on your location.

have you, or ANY of these mechanics checked all Throttle valves,AAC valves, vaccume hoses, Air flow meters, O2 sensors etc????

mind you, you have an old car you'd be suprised on whats run down or dirty or may need replacing.

check these things first before you come to conclusion for your ECU. yes an ECU is like the Brain of the engine, if faulty...it will affect your cars peformance big time. Generally speaking, the devices ive mentioned usually go...before the ECU.

MOSTLY ive seen ECU's f**k up on cars in the mid 80's era....

see how you go...

i would check the ignition leads resistance also whilst your at it.

its about elimination

Benzino33 Experienced

Benzino33

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<br />ok...<br /><br />just trying to understand things a bit more....<br />its really hard to say without seeing your vehicle...<br /><br />but from the sounds of things, id definately piss the mechanic off. shoulda pulled the plug from his first f**k up.<br />take it to someone more reputable and knows what they are doing.<br />im sure people can give you pointers as to where depending on your location.<br /><br />have you, or ANY of these mechanics checked all Throttle valves,AAC valves, vaccume hoses, Air flow meters, O2 sensors etc????<br />mind you, you have an old car you'd be suprised on whats run down or dirty or may need replacing.<br /><br />check these things first before you come to conclusion for your ECU. yes an ECU is like the Brain of the engine, if faulty...it will affect your cars peformance big time. Generally speaking, the devices ive mentioned usually go...before the ECU.<br />MOSTLY ive seen ECU's f**k up on cars in the mid 80's era.... <br /><br />see how you go...<br />i would check the ignition leads resistance also whilst your at it.<br /><br />its about elimination<br /><br /><br />
<br /><br /><br />

Hi, well yeah Ive had the car checked many times for vacuum leaks had the air flow meter looked at and ive replaced the O2 sensor. Each time I'd leave it with them and thay'd say nothing was wrong with it. When I took it to dyno, I took it to staus tuning and they said they could fix most of what's wrong, I just need a power fc. but I dont know if spending that much money on it will fix everything.They also said the restrictors have been taken off the car, so I know the stock ecu has been remapped before. Do you think its would be a good idea to try out a stocky r33 ecu? I dont have many mods and dnt have a fmic. I live in Melbourne, around Vermont, do u kno any good reputable places I can go to to have my car checked out properly?

And with coming to the ecu conclusion, I feel like its the last thing I can try, but yeah I will make sure all the stuff is checked before I purchase an ecu. I'll let u kno how I go. thanks man

Benzino33 Experienced

Benzino33

Posted
  • Author
Posted
<br />airflow meter :-)<br />
<br /><br /><br />

Ive had it looked at awhile ago and they said it was alright, but I am considering replacing it. I'll see if I can find one and let u kno

Benzino33 Experienced

Benzino33

Posted
  • Author
Posted

Bump

I think I wanna try cleaning out my afm. Is there something specific i gotta buy to clean it out? of is there anything else i can spray in there that could fix it?

WOO32 Apprentice

WOO32

Posted
Posted
Bump

I think I wanna try cleaning out my afm. Is there something specific i gotta buy to clean it out? of is there anything else i can spray in there that could fix it?

most of the time just find the closest jaycar store and buy some electrical contact cleaner, but let it dry for a good 30 mins before putting it back in once cleaned it should be ok, but if not try changing ur afm if that works but u still have some hesitation on take off also try to change ur "tps" but 90% sure its ur amf

good luck.

Benzino33 Experienced

Benzino33

Posted
  • Author
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<br />most of the time just find the closest jaycar store and buy some electrical contact cleaner, but let it dry for a good 30 mins before putting it back in once cleaned it should be ok, but if not try changing ur afm if that works but u still have some hesitation on take off also try to change ur "tps" but 90% sure its ur amf<br /><br />good luck.<br /><br /><br />
<br /><br /><br />

Ok I'll try that tomorro, I already changed my tps a couple of weeks back, got it re positioned right and it ran a bit better, but the overall problems returned, I'll see how I go tomorro. Thanks a lot man

Benzino33 Experienced

Benzino33

Posted
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<br />How much boost are you running? Because 0.6mm spark gap is way too small for my liking - try opening the gap back out to around 1mm.<br />
<br /><br /><br />

Im runnin 10 psi currently..and yeh its actually 0.8mm gapped,used to b 1.1mm and was missfiring then

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