Rb25de Feels Like It's Running Weak!

[TurboDoseBro]

Hey guys, recently swapped an RB25DE S2 motor into the R32 GTS-T. Everything seems ok but sometimes at idle it plays up (clutch in or at neutral) and i have to tap on the accelerator to make it normal again, and the power and torque feels a lot weaker than it should. Motor is stock by the way. Service has been done recently (timing belt, belts, oil filter, oil, using water as coolant at the moment to flush).

Now before everyone starts posting comments on 'search' etc i have, and these are the possible problems:

-AAC valve is dirty (dunno)

-AFM is worn (not likely i have cleaned it with AFM cleaner from Autobarn)

-O2 sensor worn (not likely as the one on the R32 worked) (also there have been rumours the R32 O2 is different from the R33 O2)

-Spark plugs (dunno)

-Coil packs (dunno)

If i do fix the idle problem, would that mean the power problem is fixed too?

Mechanic says the lack of power may be from the different fuel pumps used in both R32 and R33. So is the R32 GTS-T RB20DET fuel pump different to one of an R33 RB25DE S2?

Thanks, any input will be greatly appreciated

[xALmoN]

why would you swap out a turbo engine for a non-turbo engine?

[Shazza24]

Hah, same problem with mine but RB25DET. However going to get the place i bought it from, to investigate all the things u outlined. Warranty job! Could it be timing also?

[mad082]

Hey guys, recently swapped an RB25DE S2 motor into the R32 GTS-T. Everything seems ok but sometimes at idle it plays up (clutch in or at neutral) and i have to tap on the accelerator to make it normal again, and the power and torque feels a lot weaker than it should. Motor is stock by the way. Service has been done recently (timing belt, belts, oil filter, oil, using water as coolant at the moment to flush).

Now before everyone starts posting comments on 'search' etc i have, and these are the possible problems:

-AAC valve is dirty (dunno)

-AFM is worn (not likely i have cleaned it with AFM cleaner from Autobarn)

-O2 sensor worn (not likely as the one on the R32 worked) (also there have been rumours the R32 O2 is different from the R33 O2)

-Spark plugs (dunno)

-Coil packs (dunno)

If i do fix the idle problem, would that mean the power problem is fixed too?

Mechanic says the lack of power may be from the different fuel pumps used in both R32 and R33. So is the R32 GTS-T RB20DET fuel pump different to one of an R33 RB25DE S2?

Thanks, any input will be greatly appreciated

pretty much none of what you have listed will really affect power, at least not without some other obvious sign that it is failing. if the spark plugs or coils were the issue then you would hear them breaking down when you accelerated. they could however be affecting the idle slightly. the afm could possibly affect things, but usually there will be other symptoms. also you have to remember that if you had mods done to the rb20 (exhaust, more boost, etc) then by putting the natro 25 in you may have dropped 30 or 40hp and that is why it feels slow.

you are using the rb25 ecu? bit of a stupid question, but it has to be asked. if not then that will be the problem.

fuel pump shouldn't be an issue as far as being the wrong type, etc. it may be an issue from being dead/dying though. best way to check is to put it on a dyno. then you will see what the AFR's are doing, as well as what sort of power it makes. that will tell you if there's something wrong. it should only make about 110kw/150hp or there abouts (can vary depending on mods, etc but that is a rough estimate)

and as was said above, check the timing. check the timing with a timing light, and if it is ok then it might be worth checking that the timing belt was installed correctly.

[TurboDoseBro]

pretty much none of what you have listed will really affect power, at least not without some other obvious sign that it is failing. if the spark plugs or coils were the issue then you would hear them breaking down when you accelerated. they could however be affecting the idle slightly. the afm could possibly affect things, but usually there will be other symptoms. also you have to remember that if you had mods done to the rb20 (exhaust, more boost, etc) then by putting the natro 25 in you may have dropped 30 or 40hp and that is why it feels slow.

you are using the rb25 ecu? bit of a stupid question, but it has to be asked. if not then that will be the problem.

fuel pump shouldn't be an issue as far as being the wrong type, etc. it may be an issue from being dead/dying though. best way to check is to put it on a dyno. then you will see what the AFR's are doing, as well as what sort of power it makes. that will tell you if there's something wrong. it should only make about 110kw/150hp or there abouts (can vary depending on mods, etc but that is a rough estimate)

and as was said above, check the timing. check the timing with a timing light, and if it is ok then it might be worth checking that the timing belt was installed correctly.

lol I know what an NA should feel like, this car barely has any top end or bottom end (Example: going at 50km/h at 5th gear, i floor it and it barely goes up (if at all), compared to my dad's 1999 Celica, 6th gear at 50km/h it still goes pretty good, RB25DE: 231Nm torque compared to 2ZZ-GE (Celica): 180Nm.

Fuel pump felt ok (my narrow experiences of ok) when it had the other motor in. Mechanic showed me something about the fuel line pressure or something, he clamped one of the fuel lines softly and it seemed to run more responsive and more powerful, thus his recommendation as to find out if the RB20DET and RB25DE fuel pump was different.

Edited June 17, 2010 by TyresBro

[jrm]

lol I know what an NA should feel like, this car barely has any top end or bottom end (Example: going at 50km/h at 5th gear, i floor it and it barely goes up (if at all), compared to my dad's 1999 Celica, 6th gear at 50km/h it still goes pretty good, RB25DE: 231Nm torque compared to 2ZZ-GE (Celica): 180Nm.

Fuel pump felt ok (my narrow experiences of ok) when it had the other motor in. Mechanic showed me something about the fuel line pressure or something, he clamped one of the fuel lines softly and it seemed to run more responsive and more powerful, thus his recommendation as to find out if the RB20DET and RB25DE fuel pump was different.

Hell, I wouldn't even put my R34 GT-T into 5th gear at 50kph - 4th is about the limit, and I can't imagine how badly it wouldn't move under full acceleration. For me, cruising at 60kph in 5th sure, but even then I wouldn't floor it then - I don't think it would really 'pick up' too well (4th is a different story). These are off-boost situations for the most part, so it should be fairly similar to the RB25DE. I dunno, I think your expectations are a little off to me?

What's anyone else think?

[mad082]

lol I know what an NA should feel like, this car barely has any top end or bottom end (Example: going at 50km/h at 5th gear, i floor it and it barely goes up (if at all), compared to my dad's 1999 Celica, 6th gear at 50km/h it still goes pretty good, RB25DE: 231Nm torque compared to 2ZZ-GE (Celica): 180Nm.

Fuel pump felt ok (my narrow experiences of ok) when it had the other motor in. Mechanic showed me something about the fuel line pressure or something, he clamped one of the fuel lines softly and it seemed to run more responsive and more powerful, thus his recommendation as to find out if the RB20DET and RB25DE fuel pump was different.

accelerating at 50kmh in 5th is hardly a good basis of power. so many things come into play that make it irrelivant. for starters the weight of the car, gear ratios, cams, tune, where the car makes it's power, etc. i daresay that a 1.6L pulsar would beat a turbo rb20 by a hell of a long way doing that race

as for the fuel pump, you could put 10 massive fuel pumps in so that it could empty the fuel tank in 5 seconds and that shouldn't make a scrap of difference to how the car runs. the reason being that the amount of fuel being pumped shouldn't have any bearing on the running of the engine. if squashing the fuel line makes the car run better then it means something else is wrong. if he squashed the fuel line running to the fuel rail then he was reducing the amount of fuel, therefor something like the fuel pressure reg is stuffed, or an injector is leaking or something like that that is allowing too much fuel into the engine. if it was the return line that he squashed to make it run better then it means that the fuel pump is dead (or at least has a wiring issue) and not pumping enough fuel, or possibly again the fuel pressure reg is dead, or the fuel filter is blocked, etc. and if it isn't pumping enough fuel at idle then it sure as hell won't be pumping enough once the revs pick up.

[TurboDoseBro]

Hell, I wouldn't even put my R34 GT-T into 5th gear at 50kph - 4th is about the limit, and I can't imagine how badly it wouldn't move under full acceleration. For me, cruising at 60kph in 5th sure, but even then I wouldn't floor it then - I don't think it would really 'pick up' too well (4th is a different story). These are off-boost situations for the most part, so it should be fairly similar to the RB25DE. I dunno, I think your expectations are a little off to me?

What's anyone else think?

MAYBE you wouldn't throttle on 5th gear 50km/h in a turbo (single turbo) car, i probably wouldn't too because when the turbo isn't on boost the power torque is less than that of a non turbo. BUT, WOT seemed like a different story as the turbos begin to spool. (My experiences with RB20DET compared to other non turbos)

[TurboDoseBro]

accelerating at 50kmh in 5th is hardly a good basis of power. so many things come into play that make it irrelivant. for starters the weight of the car, gear ratios, cams, tune, where the car makes it's power, etc. i daresay that a 1.6L pulsar would beat a turbo rb20 by a hell of a long way doing that race

as for the fuel pump, you could put 10 massive fuel pumps in so that it could empty the fuel tank in 5 seconds and that shouldn't make a scrap of difference to how the car runs. the reason being that the amount of fuel being pumped shouldn't have any bearing on the running of the engine. if squashing the fuel line makes the car run better then it means something else is wrong. if he squashed the fuel line running to the fuel rail then he was reducing the amount of fuel, therefor something like the fuel pressure reg is stuffed, or an injector is leaking or something like that that is allowing too much fuel into the engine. if it was the return line that he squashed to make it run better then it means that the fuel pump is dead (or at least has a wiring issue) and not pumping enough fuel, or possibly again the fuel pressure reg is dead, or the fuel filter is blocked, etc. and if it isn't pumping enough fuel at idle then it sure as hell won't be pumping enough once the revs pick up.

Oh also another problem i read about it according to this problem is vacuum lines. (Too late to add it now)

Yes but technichally (stock for stock), if a car with less torque and power could do it from a higher gear then it should at least be a plausible way of measuring the problem. Nevertheless i shall post up some pictures tonight of the engine bay and pictures of which hose he clamped. Please stay tuned

[mad082]

Oh also another problem i read about it according to this problem is vacuum lines. (Too late to add it now)

Yes but technichally (stock for stock), if a car with less torque and power could do it from a higher gear then it should at least be a plausible way of measuring the problem. Nevertheless i shall post up some pictures tonight of the engine bay and pictures of which hose he clamped. Please stay tuned

not really, because just torque and power mean nothing by themselves. weight, gearing, etc all come into play. i'd hazard a guess that my SSS pulsar could accelerate from 50kmh in 5th gear faster than a manual 6 cylinder commodore or falcon could, despite them having about 30 or 40% more torque, because the pulsar weighs about 30% less and has shorter gearing and 50kmh in 5th would be about 1700rpm, while in a commodore or falcon it would be about 800 or 900rpm (so only just above idle).

but we are getting off topic. my main suggestion is to go put the car on a dyno. that will tell you all you need to know as far as whether there is a fuel issue, as well as whether it is down on power or not (which if there is a fuel issue then it will more than likely be affecting the power)

[TurboDoseBro]

Ok, pics as said. Clamped fuel line is circled in red, mechanic says there is a problem with the fuel pressure, which is why an RB25DE specific fuel pump was recommended.

Well, after driving it a bit more today, the power problem seems more of an air fuel ratio problem. The power is on and off sometimes and in different ranges of the RPM, sometimes a particular gear may feel 'alright' and sometimes just feels sluggish later on. May be because i bought a cheap 2nd hand AFM I'll try changing sparkies and maybe coils first and see how it goes...

Edited June 17, 2010 by TyresBro

[La Bomba]

Ok, pics as said. Clamped fuel line is circled in red, mechanic says there is a problem with the fuel pressure, which is why an RB25DE specific fuel pump was recommended.

Well, after driving it a bit more today, the power problem seems more of an air fuel ratio problem. The power is on and off sometimes and in different ranges of the RPM, sometimes a particular gear may feel 'alright' and sometimes just feels sluggish later on. May be because i bought a cheap 2nd hand AFM I'll try changing sparkies and maybe coils first and see how it goes...

make sure u have an rb25de ecu and loom. that may be the problem.

[TurboDoseBro]

Definately using RB25DE loom and ECU and AFM. Thanks.

Beginning to think that the AFM is the problem here, contributing factors:

- Power and consistency through RPM varies a lot

- Feels sluggish msot of the time like there isn't much power being produced through the air-fuel ratio (feels restricted), whereas others times it feels ok

- Sometimes tapping on the throttle actually moderately a few times sees (feels) power gains coming back at the same speed, RPM, and gear (maybe the ECU is correcting it's AFR gradually)

- Sometimes all throttle % feels roughly the same (maybe bad signal to ECU)

Any thoughts or 2c?

[TurboDoseBro]

UPDATE: Before changing the spark plugs and fuel filter the car seemed to be healing itself, after the change it seemed to run a bit funny for a while, then familiarized. It's almost like the ECU is adapting. Now it's running alright but when the engine is still cold it plays up a bit. Normal?

Edited June 21, 2010 by TyresBro

[Jdfnq]

Have you re-set the ECU recently???

[TurboDoseBro]

No actually not yet, i have heard different stories about resetting the ECU:

Unplug a terminal from battery and drain all electrical power from the car by stepping on the brake pedal, then reconnect and start. Apparently this doesn't fully reset the ECU so i didn't bother incase it just puts the car back in it's crappy running state.

Use a paperclip to short circuit two connections on the inside fuse box for about 2 seconds and the check engine light will start flashing. This tutorial was done for an R33 and i can't find the connections for the R32 so i didn't try.

Any suggestions?

[mad082]

the amount that the ecu learns is actually pretty small, so i would try resetting it via the disconnecting +ve battery terminal method in order to clear any possible fault codes and get it back to the stock settings.

[FrangaR33]

not really, because just torque and power mean nothing by themselves. weight, gearing, etc all come into play. i'd hazard a guess that my SSS pulsar could accelerate from 50kmh in 5th gear faster than a manual 6 cylinder commodore or falcon could, despite them having about 30 or 40% more torque, because the pulsar weighs about 30% less and has shorter gearing and 50kmh in 5th would be about 1700rpm, while in a commodore or falcon it would be about 800 or 900rpm (so only just above idle).

but we are getting off topic. my main suggestion is to go put the car on a dyno. that will tell you all you need to know as far as whether there is a fuel issue, as well as whether it is down on power or not (which if there is a fuel issue then it will more than likely be affecting the power)

+ 1 its all about the gear ratio's, falcons and commodores are designed to have longer gears so therefore more economy especially in their top gear so accelerating from in 5th gear would be a painfully long experience. Clarkson showed a perfectly example albeit with a turbo car when he raced in 5th or 6th gear a Skoda Octavia diesel vs a EVO 8 or 9 over a mile long race and the EVO got killed.

[mad082]

+ 1 its all about the gear ratio's, falcons and commodores are designed to have longer gears so therefore more economy especially in their top gear so accelerating from in 5th gear would be a painfully long experience. Clarkson showed a perfectly example albeit with a turbo car when he raced in 5th or 6th gear a Skoda Octavia diesel vs a EVO 8 or 9 over a mile long race and the EVO got killed.

yeah i was trying to remember what the cars were in that episode cause i was going to try to find a youtube video to post.

this is also part of the reason why NA skylines can keep up with commodores and falcons. put a big aussie 6 or v8 diff ratio into a NA skyline and it would get left for dead. even a lot of relatively stock turbo skylines would struggle against the big aussie 6's.

alternatively, put a small car diff ratio into a commodore or falcon and you'd never get over about 50% throttle in first without frying the tyres. you could easily take off in second cause it wouldn't be that much harder than first gear is normally. 2nd gear in a manual skyline is about the same ratio as first gear in an auto falcon/commodore. go and try and take off hard in 2nd gear and see how slow it is. puts the performance of the big aussie 6's and 8's into perspective.

[TurboDoseBro]

Ok cool. Thanks guys, will try and also report.

yeah i was trying to remember what the cars were in that episode cause i was going to try to find a youtube video to post.

this is also part of the reason why NA skylines can keep up with commodores and falcons. put a big aussie 6 or v8 diff ratio into a NA skyline and it would get left for dead. even a lot of relatively stock turbo skylines would struggle against the big aussie 6's.

alternatively, put a small car diff ratio into a commodore or falcon and you'd never get over about 50% throttle in first without frying the tyres. you could easily take off in second cause it wouldn't be that much harder than first gear is normally. 2nd gear in a manual skyline is about the same ratio as first gear in an auto falcon/commodore. go and try and take off hard in 2nd gear and see how slow it is. puts the performance of the big aussie 6's and 8's into perspective.

Yes, but HOWEVER as you mentioned in the earlier posts, weight is a big issue AS WELL AS gear ratios. I doubt a small car ratio is enough to transform these Fords and Holdens into drag machines considering they weigh roughly 1700kg tare.