[Mountain Lion]

Half way through the journey home on Thursday evening, as I was approaching a red light, I pressed the clutch pedal down in preparation to stop the car.

Imagine my surprise as the revs shot up to about three and a half thousand rpm, stayed there until the car came to a standstill, and then dropped to just above idle speed a second or two later. “Funny”, I thought.

The engine continued to do this for the rest of the journey. Every time I dipped the clutch to change gear or stop at a junction, the revs would shoot up. The FRP isn’t the quietest of cars, so it attracted a bit of attention. The following day, I was able to drive to work down the motorway with my foot completely off the accelerator pedal.

I would have automatically assumed that the accelerator pedal, the throttle cable, or the throttle assembly was sticking. However, there was one thing that was bugging me. Why did the revs only return to normal (or near normal) only after the car had come to a complete standstill? I guessed that it was something electrical rather than mechanical.

Browsing around the Pumapeople website, I came across a few threads that suggested the Throttle Position Sensor as a likely culprit. This tied in with my theory that the problem was electrical, so I bought and fitted a new one, disconnected the battery for half an hour to reset the ECU, and took the car out for a test drive. Unfortunately, the problem was still there, although disconnecting the battery had restored the Clifford alarm’s arm/disarm chirp (which scared the crap out of me when I reconnected the battery lead). So, back to square one then.

With the engine off, I depressed the accelerator pedal. Lo and behold, it stayed down when I lifted my foot off it. So it was mechanical after all – the revs not dropping until the car had stopped was a red herring. I can only assume that it’s the ECU up to its shenanigans that causes this behaviour.

I checked the pedal, which seemed to be moving freely, and then checked the throttle assembly and return spring, which all seemed OK. Then I noticed that the throttle cable had quite a sharp bend in it, as shown in the following picture…

I know from experience that cables don’t respond well to being bent at sharp angles. I tried to straighten it out, but there wasn’t enough slack in the rest of the cable to do this, mainly because the following had been done a couple of years ago…

The picture shows a fix for the infamous FRP vibrating accelerator pedal. The throttle cable has been clamped to the air conditioning pipe with a cable tie. I cut off the cable tie, which allowed me to straighten out the bend in the throttle cable.

After taking the car out for a short drive, I can confirm that this has fixed the problem in the short term. I’ve ordered a new throttle cable, which I’ll be fitting next week.

So what’s the moral of this tale? Well, there are several. Firstly, investigate the problem fully before shelling out money on sensors. Secondly, modern computer-controlled engines can sometimes throw you off track when trying to diagnose a problem. And thirdly, I don’t think that tying the throttle cable to the aircon pipe is such a good idea. I haven’t tried the car at 70mph in fifth yet (which is when the vibrating accelerator pedal phenomenon usually happens), but I’ve heard that simply wrapping convoluted sleeving around the aircon pipe is enough to reduce the vibration to an acceptable level.

Until next time, happy motoring.

[Condici]

Crikey! Wish I had this knowledge of cars.

[pumarv6]

A cable tie wasn't part of the Ford installed fix for the vibration problem, so the problem might be unique to FRPs where owners think they are being helpful by fitting one.

Something to keep in mind too, is that the Ford fix for sticking throttle issue required a replacement of the TPS sensor and some wiring changes to the TPS loom.

[Mountain Lion]

A cable tie wasn't part of the Ford installed fix for the vibration problem, so the problem might be unique to FRPs where owners think they are being helpful by fitting one.

In my particular case, it wasn't an owner that carried out the fix, but one of the well-known Puma specialists.
So if anyone has had the fix done by an independent garage, they might like to have a look at their throttle cable.

Something to keep in mind too, is that the Ford fix for sticking throttle issue required a replacement of the TPS sensor and some wiring changes to the TPS loom.

Technical Service Bulletin No.25/2002 covers this work, which basically involves fitting a new TPS electrical connector and fitting three patch wires, so that instead of passing through the main engine harness electrical connector, the TPS wiring completely bypasses it. It was the first job I ever did on the FRP. As it happens, it made no difference to my car - the evidence suggests that my particular problem at the time was caused by a Ford workshop using the standard cam locking tool to change the timing belt.

I have my doubts about this TSB. I've yet to hear of it making a difference to anything except Ford's coffers. I think happy-kat had it done, but she also had some other work done at the same time, so it's difficult to say what made the difference to her FRP.

[pumarv6]

I had the sticking throttle issue on my FRP back in 2002. A new TPS and the wiring changes were carried out as per TSB 25/2002 - the problem was solved and has never re-occurred since

[Mountain Lion]

I stand corrected.

[pumarv6]

Not correcting, just adding my particular experience.

As you point out, if other FRPs have had this tie-wrap fitted by a Puma "specialist", then maybe they run the risk of a similar problem. It's a good heads-up

[happy-kat]

I had the TPS work and wiring change done plus the ECU updated to the last FRP map. But my problem was not sticking revs, but stalling often which was fixed by the changes thankfully.
I have had the odd occasion of sticky revs since, without fail every year driving home after Ford Fair yet I don;t get it if say I go to Brands... but Ford Fair has been super hot

[Hansie]

Recently we have fitted the FRP inlet manifold. Now we have vibrations in the accelerator pedal round 4000 RPM. Because of the FRP inlet manifold the throttle body is closer to the battery box and the throttle cable is more bended now.
I think the inlet manifold is resonating at about 4000 RPM. This causes the throttle cable and accelerator pedal to vibrate. So damping the throttle cable will reduce vibration in the accelerator pedal.

[Mountain Lion]

I can't help thinking that Ford should have made a longer cable for the FRP.

[Mountain Lion]

I’ve just had a look at the throttle cables on both the FRP and the standard 1.7.

The FRP cable is secured to a small plate that’s been welded to the middle of the bonnet slam plate (just in front of the inlet manifold) by two plastic clips.

The standard Puma is secured to a similar plate, but is also secured to the bonnet slam plate further to the left, in front of the aircon pipe. Because the throttle assembly is lower and further to the left than the FRP, there’s enough slack in the cable to be able to do this without introducing a tight bend in it. There isn’t on the FRP.

Also, the aircon pipe has been bent into a different shape on the FRP, probably to accommodate the inlet manifold.

My theory is that because the FRP’s cable is not secured in as many places as the standard Puma’s, and it runs next to the aircon pipe, which it doesn’t on the standard, either through resonance or simple conduction of engine vibration, the cable slaps against the aircon pipe. This might be why wrapping a sleeve around the pipe serves to dampen the vibration felt through the accelerator pedal.

[Mountain Lion]

Well, the saga continues...

This morning, on the way to work, in the outside lane of a busy dual carriageway, the throttle cable snapped.

Not for the feint-hearted, I can tell you. It snapped at the point that had been bent at a sharp angle due to being tied to the aircon pipe.

By sheer fluke, I picked up a new cable on Wednesday (which I was going to fit tomorrow), and still had it in the car. The (very) nice man from the AA kindly fitted it for me, after having escorted me at idle speed through a series of roundabouts, dual carriageways and one-way systems to a retail park.

I would offer the following advice to any FRP owner who's throttle cable has been placed under adverse strain due to being tied to anything...

REPLACE YOUR THROTTLE CABLE AS SOON AS POSSIBLE!

[pumarv6]

If a garage had done such a thing on my vehicle that had caused a failure, I would hope they would absorb the cost of replacement parts and labour.

[happy-kat]

very useful thank you, what a brown trouser moment for you

mine looks like this so hopefully when I look I wont find a tie

[Mountain Lion]

A piece of advice for anyone replacing the throttle cable themselves - don't throw away the old cable until you've fitted the new one. There's a metal clip that needs to be removed from the old cable adjuster and fitted to the adjuster on the new cable.

The vibrating pedal's back with a vengeance now, but I think I'd rather have that than the hair-raising experience I went through this morning. I might investigate ways of securing the long length of unsecured cable without stretching it.

The trademark pops & bangs from the exhaust are also back with full force . I hadn't really noticed, but I think they must have gradually diminished as the cable got stiffer.

Happy-kat - I think your cable may be OK. One thing I didn't mention was that my picture of the bend in the throttle cable was taken after I'd attempted to straighten it out (but before I'd removed the cable tie from the aircon pipe). The bend was actually more acute than shown in my photo when I first spotted it.

[Assimilate]

Hi there

I am resurrecting this thread because I am starting to experience the same problem!

Was driving on Saturday and car started over revving - even when braking on approach to roundabouts and junctions the engine was still revving over 4000rpm and only settled down to 1000rpm once the car came to a complete standstill.

Driving to Nottingham this morning the same thing happened again. I could take my foot off the accelerator and quite happily cruise at 40mph. When it's over-revving if you lift your foot off then the pops and bangs from the exhaust don't happen either. However, when I was moving off from some traffic lights I managed to stall the car as I was in 3rd and not 1st but after this slight embarrassing moment I pulled away and it stopped over-revving for the rest of my journey

Driving back from Nottingham the car behaved itself perfectly.

So, do you think I have a sticky throttle cable, or do you think it could be a sensor on its way out, or the ECU needs re-setting?

What with this and my massively squealy brakes I must have the noisiest FRP in Derbyshire LOL

[Mountain Lion]

As far as I can tell, the problem can be cause by any one (or a combination) of the following...

• Sticking accelerator pedal
• Sticking throttle cable
• Sticking throttle assembly mechanism
• Faulty throttle return spring
• Faulty throttle position sensor
• Faulty wiring to the throttle position sensor

[W4FRP]

I experienced this problem when driving home after the alcantara run to the Frogmill Hotel. Exactly the same symptoms as mentioned above. I let it cool down on the drive for an hour and then took it out for a test run and the problem was still there. I spent ages checking throttle linkages, return springs, cable run etc etc but there was nothing wrong with anything mechanical. The pedal always came back up and wasn't sticking even when the revs were at 3500. I put it down to something electrical and decided to wait and see if it happened again. I took the car to work the following morning and he was fine and it hasn't happened again since.

From your list Mountain Lion, I could only say it was TPS as I checked all other possibilities. I haven't bothered changing it as it hasn't happened since !!