Hi wondering if someone could please help me, I just bought a VL turbo which is running a standard rb25 with hks airfilter/ front mount and is running standard boost.. it has been running fine the first few days since i had it, but now everyone time i put my foot down when it starts to spool, it jumps (like boost cuts out then goes back on) mate has a r33 and said its either airflow meter or maybe wastegate???? but thought id ask on here.. cheers

Quote: Originally Posted by VLT025 I just bought a VL turbo which is running a standard rb25 with hks airfilter/ front mount and is running standard boost.. i.e. my old car.. 1) Did you increase the boost? 2) Does the car have more than 1/3 of a tank of fuel? 3) Are you using 98 oct fuel? 4) Have you lost my phone number?

Is it farting or blowing black smoke on idle? Is it a pig off boost just cruising? These are some signs that the afm is causing some probs. Also, does it only happen when the car is warmed up? The problem sounds electrical to me, someone with more knowledge may be able to pinpoint the problem better than me. Try getting some electrical contact spray (CRC), spray it on your AFM plug and plug it in and out a few times to clean it out. Then unplug and leave it to sit until dry, then when it is plug it back in take it for a drive.

Does the RB25 computer have a diagnostice setting like the rb30 standard ecu?? with the rb30 Id Reset all the stored codes go for a drive and get it to do what was happening, get home and cheak the codes and walla

Hmmm sounds liek to me it is mifiring am i correct? which means it could be the ignitor on its way out and it isnt firing corecttly this is a common problem on Coil pack RB engines like RB20/25/26 sounds liek ur spark is going out thats all or ignition problem. just get it checked out with the AFM it usally would go crap without boost aswell i have no AFM on my RB25 so i dunno how it goes without 1 but when my AFM on myt TX3 turbo went it would stall before i could drive it.

This is my old car. It's just the usual RB25 R&R and not doing anything it hasn't done previously. I told geoff to get the spare ECU modified as I suggested when he picked it up and he will not have this problem anymore Some original photos have not been recovered yet.

Just asking why would a modified ECU fix the problem? If its only got those small mods it should run sweet as. but i do know with the less fuel when you boot it it really surges.

Quote: Originally Posted by HYBRID VL Just asking why would a modified ECU fix the problem? If its only got those small mods it should run sweet as. but i do know with the less fuel when you boot it it really surges. It's a common issue with R33 skylines running intake/exhaust mods on standard ECUs. They don't run crap, but from time to time you get this sort of soft rev limiting and popping sound between 4500-5500rpm. It boils down to the spark breaking down because of the ECU dumping too much fuel in and retarding the timing (as a protection measure) when it sees a lot of airflow making it hard to fire the spark at that point. The fact that it does this at near std boost illustrates how efficient the intake/cooler/exhaust is. The modified ECU will allow it to rev cleanly instead of popping at those revs, fouling the plugs, which then puts stress on the coils etc etc. The dyno chart I have shows the mixtures getting ridiculously rich when under load at high revs. I guarantee if he were to turn the boost down 2-3PSI at the moment it would never do this. It's not so much of an issue if you change plugs often, but ultimately the problem lies with the ECU, and this car will make over 200-210rwkw easily with this done and 12-14psi on the std turbo. Just make sure you install those pumps I gave you too geoff!!

Quote: It's a common issue with R33 skylines running intake/exhaust mods on standard ECUs. They don't run crap, but from time to time you get this sort of soft rev limiting and popping sound between 4500-5500rpm. Yeh I had this problem once on the freeway a couple of weeks ago. At least now I know its not a major problem.

VLT-025 is absolutely correct. The standard RB25DET ECU has a rev, speed limiter and boost cut which will retard the timing and increase fuel to protect the engine against excess load. The symptoms VLT025 described are typical of the spark problems with increased airflow. Buy an aftermarket ECU such as a PowerFC because they do not have a rev, speed or boost limiter. I ran a mines ECU in my old RB25DET calais which is just a remap of the standard ECU with the rev, speed and boost limiter removed. Are you running standard coil packs? I'd check them out too.

You're right but a power FC is overkill for what he will need. Given the $12-1500 price tag these are commanding, I think a re-map is MUCH better value. This can be done in real time for around $500 if you go to the right person. The standard ECU is actually a pretty powerful and underrated bit of gear and has a lot of protection smarts built in e.g. if one of your engine sensors go it can usually compensate and still drive the car safely. It won't run massive injectors, but for a car running around 250rwkw or less it is perfectly sufficient with little if any drawbacks.

As for the PowerFC or similar, it depends on the modifications he has planned down the track. I agree regarding the remaps, hence why I ran one in mine as I was more than happy with my mild setup. They are excellent value for money.

Get a Microtech on that price mate the power FC is good but you need Jetroso u can get rid of the AFM. yer saying about that sensor thing that gives it more fuel to protect the engine i know what ur talking about but take my warning i wouldnt take a Rev limiter off mate engine are usally built to only rev to the certin limit mate. i still think its ur coil packs or ignitor.

Quote: Originally Posted by HYBRID VL but take my warning i wouldnt take a Rev limiter off mate engine are usally built to only rev to the certin limit mate. You can set it to whatever you want. Of course only a retard would set it to 9000 or remove it completely Quote: Originally Posted by HYBRID VL i still think its ur coil packs or ignitor. and what do you think causes these to fail? If you were to address this only, it would just be a band aid solution. I doubt they would be any problem as I inspected them carefully only months ago. FYI the problem dissappears with new plugs too...doesn't mean they won't foul again in the future. As for installing a microtech...why the hell would you bother? You have to re-wire it, tune it and still have a sub-standard ecu that regency would frown on highly, while paying upwards of $1000-1500 for the job if you use a second hand ecu. There's nothing wrong with running an AFM either Anyway, it's not my car anymore..I can only suggest things that I spent a long time researching. It's up to the new owner now