Ford Puma 1.7 with very high RPM on idle.

[sirrjm]

Greetings everyone, I recently got my hands on a 1.7 ford puma that I am doing a restoration on. But the car has a very high idle rpm which is also not stable.
My mechanic is having a slight problem tuning it, since he either overtunes it or undertunes it. It either gets to the point where the RPM spike at like 8000rpm after breaking (they go calm after changing to neutral), or normal RPM but on the second shift it has no power at all under full throttle.

He also found a tube that is stopped with a screw, which he thinks some kind of pump should go there but he doesn't know what is it for.
Does anyone know what this tube is for?
View attachment IMG_20231222_185330.jpg
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Thank you.

 

[YOG]

That's where a blanking plug normally is. They often split and fall off and that's a normal way of fixing it. Unless there is an air leak there it should be OK.

 

[sirrjm]

That's where a blanking plug normally is. They often split and fall off and that's a normal way of fixing it. Unless there is an air leak there it should be OK.
View attachment 11678

I really appreciate the reply, it will very helpful when I relay this information back to the mechanic, we can try to figure out what else could be causing these problems.

 

[mredd65]

Greetings everyone, I recently got my hands on a 1.7 ford puma that I am doing a restoration on. But the car has a very high idle rpm which is also not stable.
My mechanic is having a slight problem tuning it, since he either overtunes it or undertunes it. It either gets to the point where the RPM spike at like 8000rpm after breaking (they go calm after changing to neutral), or normal RPM but on the second shift it has no power at all under full throttle.

He also found a tube that is stopped with a screw, which he thinks some kind of pump should go there but he doesn't know what is it for.
Does anyone know what this tube is for?
View attachment 11676
View attachment 11677
Thank you.

Could be the tps throttle position sensor had a similar problem put a new one on £14

 

[Wild E. Coyote]

#1, #2 and #3: Check for unmetered air what equals to basically any vacuum leak. Namely: servohose pulling vacuum from inlet manifold, vacuum hose for fuel pressure regulator, the Y shaped rubber hose going to PCV valve. My bet is that Y shaped hose below inlet manifold is perished what, given the age of car, is to be expected, I guess. Also worth checking: PCV valve (the blue arrow).
After you are 100% sure that all is sealed as it should be (don't forget inlet mani seal) pursue other options including replacement of any sensors and switches. If you are having problems only at gearshifts, have a look at neutral switch (on the clutch pedal telling ECU that you are shifting gears).
For proper idle engagement you need proper signalling from: MAF (determinig the ammount of air entering the engine). MAF is most probably baked in oil residue (it should be shiney element, most probably is black and full of s..t) affecting idle and throttle pickup. Next: IAT on inlet manifold. TPS -> Testing TPS
Finally, engine should be warmed up to engage proper idle of 800/ish rpm. ECU will know that according to the signal of coolant sensor.

Good luck

 

[sirrjm]

Greetings again, this was after all a timing belt replacement/tensioner replacement (actually OEM one), and trying to tune down the idle RPMs. Now a second attempt was made and the mechanic took out the plugs around the air intake sensors (near the air filter) and put them back in, and that seems to have done something to calm down the behavior of the car, now it doesn't die or have extreme RPMs after breaking, but the only fault it has currently is that the car just can't floor it anymore, it can go from low to high rpm if you slowly gas it, but if you floor it it will instantly choke out until it fails. Specially bad trying to get a steep incline in first gear.

 

[GreenEyedPuma]

sirrjm,

Hi, re the remaining "floor it", or steady acceleration difference, could it be a sticking accelerator cable? It might move ok under gradual movement, but stick on a sudden movement, possibly?

Also, is it the correct cable - the "stretchy" one, specific to the Puma, I think? The Puma cable was 2-part, with an inline device (over the timing / cam belt cover area), supposedly for the laughable "Anti Wheel Spin" system, which used it to reduce revs, if wheelspin in mud / ice, etc. was detected. It didn't really work! Somebody may have tried replacing it with a standard Fiesta one, resulting in your problems?

I don't have any photos of what I've mentioned, but hopefully anybody on the site might be able to post some, for reference / ease of identification!

I had to replace mine when it was about 12 years old. Actually now thinking back, my car razzed the engine to max when I stopped at a Pelican Crossing and I got filthy looks from the people using it, until I switched off and hazards on. Then I gently pumped the pedal a few times and started up again. It worked fine then, but did it one more time a couple of days later, then the cable snapped on the Motorway. I pulled out into the outside lane after a fast car went by, floored it and the pedal dropped to the floor!!!

Meanie wagon drivers wouldn't let me over, with them passing me up the inside, whilst I was slowing down in the middle lane - scary!!!

The accelerator cable had turned to fluff, under the retaining / hand blip bracket on the throttle body.

Hopefully your mechanic has checked that all, but you never know! Good luck finding the cause anyway!

 

[sirrjm]

Hello again, the car is working now, I can't say I don't know really what was wrong with it, the mechanic shrugged it off as "the previous owner installed the butterfly valve wrong" and left it at that, but the car was fine with me for a while and this only happened after the serpentine/tensioner replacement. I feel like he messed up and just can't admit it.

I wish I knew what it was actually wrong because some other person might run into this problem one of these days, but thanks everyone for the reply.