Acceleration *hiccup/hiccough*

[Junosi]

I've had an intermittent problem for a few months now, which seems to be becoming a more regular or constant problem recently. Under moderate to heavy acceleration it will often hesitate or hiccup, generally just prior to a gear shift up and most noticeable changing from 2nd to 3rd at around 55-60km/h. Revs drop off sharply and return as if I were pumping the pedal up and down - usually only for a second then carries on accelerating. It doesn't do it under light acceleration. It's present on both LPG and petrol

I've had the faultmate on it and it's returning no fault codes, also logging the engine data isn't turning up anything unusual - except that it's noticing my revs pulsing at the time it occurs. First thoughts were the the MAF is faulty, so replaced that with a known good one. Still does it and with the MAF unplugged the problem is worse. Second thought was one of the myriad of electrical connectors so unplugged/plugged cleaned all that I could find. Still doing it.

Latest thought is that its my throttle position sensor. I took the TPS off and hooked it up to a multimeter and it appears to give good readings throughout its range. The interesing thing that makes me think it's the TPS is that if I unplug the TPS and go for a little drive (5mins), the engine feels more powerful but has great trouble deciding when to shift - as expected with the shifting. When the TPS is plugged back in, everything seems to be fine again for a week or so - no hesitation. Done this a couple of times over the last few weeks but the hesitation returns eventually.

Faulty TPS you think or something else still ?

[DT-P38]

The pig had similar symptoms one time due to issues with the crank angle sensor. She used to hit a point in the rev range and just drop away/break down (like as in spark break down).

I'm no mechanic, but it might be worth looking at your crank angle sensor as well.

[redandy3575]

I've got a similar problem with that also, along with the hard to start issue in my other post. We need a mechanic!!!!:o

[GuyG]

Mine was doing the same as you are suggesting, very scary when you go to overtake a semi and it hesitates:o, even worse when you have another vehicle behind also attempting to overtake. It was intermittent, but could never get it to show fault when at the mechanics. Turns out that it had registered a fault on the computer. Had it replaced, the first one the mechanic got in was faulty before it was even fitted to the car, the second one lasted less than 3 weeks, although it didn't register a fault on the computer. So fingers crossed on the third one that was fitted this week.

[Junosi]

Mine was doing the same as you are suggesting, very scary when you go to overtake a semi and it hesitates:o

Agreed!


Had it replaced

Had the engine ecu replaced?

[willem]

Mine does it too! Cures your constipation when it happens at just the wrong time!

So far I've only noticed it on LPG, probably because I hardly ever run on petrol. Most often after the car has been in overrun, like when accelerating out of a corner after coasting into it.

It's be great to get a solution for this one.

Willem

[GuyG]

Agreed!

Had the engine ecu replaced?

No, just the TPS, but this was in the classic rangie with v8. Can't imagine that that would make any difference though.

[Junosi]

Well I've ordered a new TPS from Graeme at Britcar in Melbourne - he's always helpful. TPS is $114 - oddly one of the few parts that doesn't seem to be available via UK eBay or other online shops that I can find.

I'll let you know how I get on with the new one. If it's still doing it then I guess I'll move on to the crank sensor. Annoyingly it's behaving itself at the moment so I'll have to wait until it's playing up again before swapping in a new tps

[redandy3575]

Well I've ordered a new TPS from Graeme at Britcar in Melbourne - he's always helpful. TPS is $114 - oddly one of the few parts that doesn't seem to be available via UK eBay or other online shops that I can find.

I'll let you know how I get on with the new one. If it's still doing it then I guess I'll move on to the crank sensor. Annoyingly it's behaving itself at the moment so I'll have to wait until it's playing up again before swapping in a new tps

Sounds like i'd have to follows suit. What's the number for Britpart and will he post it out via phone order???

[Junosi]

03 9329 5766 for Graeme at 'British Car Components', info@britcar.com.au British Car Components - spares and parts for British cars, Melbourne Victoria, Australia (http://britcar.com.au/)

I don't know about phone order and postage, I've always picked em up. His prices are usually quite competitive (for Australia), also they are always plus gst.

Clark

[Junosi]

Just a quick follow up to this. Replacing my TPS with a new one seems to have cured my problem. The old one tested fine and appeared to give all the right voltages etc but guess it was tempermental.

[redandy3575]

Just a quick follow up to this. Replacing my TPS with a new one seems to have cured my problem. The old one tested fine and appeared to give all the right voltages etc but guess it was tempermental.

Yeah i replaced my TPS also, however it turned out to be the fuel pump in the end. After replacing that the power is back and the flat spot between 1500rpm to 2000 is also gone with extra power to spare. It feels like driving a new car again, after cleaning the throttle body, stepper motor, MAF sensor and the TPS. However i'm still dealing with the radiator, which will be next soon. BTW do not go to NATRAD..... they know nothing about P38's let alone how to remove the radiator... I got out of there quick smart.

[BusinessConnected]

redandy:
It's been widely proven around here that removal/repair of Radiator is pointless... they almost always break.... Best to just get a New OEM one from BritishParts or similar for around $400...

[RR P38]

Have you changed the fuel filter under the drivers door(on chassis rail)?

WARNING: if you undo it wear some safety glasses it is well pressurised fuel will spray all over the place if you dont wrap it as you undo it.

It could also be your in tank pump.

[redandy3575]

redandy:
It's been widely proven around here that removal/repair of Radiator is pointless... they almost always break.... Best to just get a New OEM one from BritishParts or similar for around $400...

Have ordered a new one from graeme should get here around Thursday i hope.