What short journies do

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Mon 5 Oct 2009 21:20
What short journies do - bathtub tom
I was out in the old KIA Pride yesterday when I noticed a drop off in performance. It had lost it's edge at the top end. It'll happily rev to 7K normally but it suddenly was topping out at 6K, this was in first with the foot to the floor.

It would happily get to 4K, but then struggle any further.

I checked the carb, thinking it felt as if the second choke wasn't opening. I could see the first open on the cable operation, but can only assume the second is controlled by vacuum and throttle opening. I wasn't prepared to try that stationary.

It's got a crude EGR, where a bleed off the cat feeds directly into the air filter (no valve). This seemed excessive and noisy. Checking the exhaust outlet, that seemed muted without the usual pulses. I've heard of collapsed cats (yes it's got one).

I pulled the cat off and could see that was no problem, so I thought I'd check the rest of the system. The back box rattled. The exhaust has been on less than three years and is showing no signs of external rusting.

i353.photobucket.com/albums/r370/bathtubtom/S63004...g

The little pile of black bits is what I assume to be the perforated tube that runs through the box. It seems this rusted through and allowed the wadding to block the exhaust path, increasing back pressure and forcing more exhaust through the EGR.

The back box is now completely empty, I can see right through it, but stangely the car isn't any louder.

I guess it doesn't get enough long journies. It'll be interesting to see how long the casing lasts. There's no sign of any rust on the outside.

Took it down the road, 7K in first and second, no problem.

The missus would like to know the reason for putting all that stuffing in there.

I'd still appreciate anyone telling me how the second choke on the carb is operated.
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Mon 5 Oct 2009 22:24
What short journies do - Graham567
In the picture it looks like the cat(cough) has been fired into the back box.It looks just like a real cats fur!!!.

Awesome!
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Mon 5 Oct 2009 23:15
What short journies do - vulcan7
Not sure about short runs. I have had this problem with two cars in our family one was on shorter runs but the other wasn't both Nissans.

Again perfect when I got all the stuff out and made no difference to the noise as I could tell.

Put it down to cheap manufacture first one took me a bit to diagnose second easy.
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Tue 6 Oct 2009 09:31
What short journies do - perro
Was the back box OE bathtub, or a pattern?
The stuffing is to muffle the sound, hence muffler.
In my tuning days, a restriction in the exhaust system would have showed up on the vacuum gauge i.e. much lower than normal, a vacuum gauge is/was a pretty handy piece of kit when one learnt how to read the critter ... of course I'm not talking about todays jamjars :)
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Tue 6 Oct 2009 11:37
What short journies do - bathtub tom
>>Was the back box OE bathtub, or a pattern?

It's a '93 model perro. I think the main dealer would laugh me out of the shop if I went there asking for parts.

Thank goodness for motor factors.
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Tue 6 Oct 2009 11:54
What short journies do - perro
>>> It's a '93 model perro <<<

Say n'more tom! Did the car come with whitewall tyres as I seem to remember seeing some?
Are some parts interchangable with the Fiesta or Mazda 121 of that year I wonder?
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Tue 6 Oct 2009 13:08
What short journies do - bathtub tom
I was told the Mazda 121s came with whitewall tyres as standard. My Pride has got one - I hope it's not an original.

Their history is detailed in CBC above. They are/were Mazda 121s (Ford Festiva in USA).

When I bought the exhaust, the factors said 'sfunny, thats a mix of Ford and Mazda part numbers.

I only bought it because the previous owner was going to scrap it (£50). It's very softly sprung and lightly damped. It wallows and doesn't really like going round corners. It's light (800Kg) and pokey (1324cc twin-choke carb).

It all makes it a hoot to drive!

I'm very impressed with the way it's been put together. Underneath has less corrosion than my daughter's six-year-old MX5.
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Tue 6 Oct 2009 14:14
What short journies do - perro
>>>It's very softly sprung and lightly damped. It wallows and doesn't really like going round corners<<<

Ah! bit like the ole Renault 5 then :)
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Tue 6 Oct 2009 09:33
What short journies do - Harleyman
I was out in the old KIA Pride yesterday

The missus would like to know the reason for putting all that stuffing in there.



That would be because the Kia Pride was a turkey.



I'll get me coat...........
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Tue 6 Oct 2009 10:01
What short journies do - perro
>>> That would be because the Kia Pride was a turkey. <<<

Not a bad little mota was the Pride, one of the 1st imports from Kia into the UK and an ideal little runabout IMO.
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Tue 6 Oct 2009 13:16
What short journies do - Number_Cruncher
>>The missus would like to know the reason for putting all that stuffing in there.


It is there to provide acoustic absorption or damping.

Silencers will work reasonably well without any absorption material in there, becasue there are two sudden changes in section. When an acoustic wave meets a change in section, this represents a change in acoustic impedance, and, some of the wave is reflected back up the pipe. The silencer effectively acts as a trap with the wave bouncing back up and down its length, and only a small portion getting out of the end of the pipe.

While the impedance mismatch effect above makes the waves bounce around, there isn't any mechanism there to actually dissipate any of the wave's acoustic energy. By interacting with the acoustic waves, the absorption material will act to turn the acoustic energy into heat energy, and thus further reduce the sound pressure.

>>I'd still appreciate anyone telling me how the second choke on the carb is operated.

I don't know much about these cars, but, if it's not a straight forward linkage, then, it's most likely vacuum operated from the first venturi.

Edited by Number_Cruncher on 06/10/2009 at 13:18

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Tue 6 Oct 2009 13:59
What short journies do - Cliff Pope
>>
I don't know much about these cars but if it's not a straight forward linkage
then it's most likely vacuum operated from the first venturi.


I had one like that on a Volvo. Movement of the first throttle spindle past a certain point permitted the spring-operated second to move, but it didn't do so until actually activated by a vacuum device.
You could test it by moving the first manually (engine off), then sucking on a pipe to simulate the vacuum. If nothing happened then either the diaphram was punctured or the mechanism was stuck. This could easily happen if you hardly ever pressed the pedal down far enough to keep it free.
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Tue 6 Oct 2009 14:39
What short journies do - Harleyman
Odd little car...... like Ladas and Skoda Estelles, they tend to have a loyal band of devotees who defend them to the hilt despite their acknowledged failings.

My experience of them is via Mrs. H who had one when we first met. Have to admit it pulled well and the headlights were good, but reliability wasn't its strong point. Can't say I was overly impressed with it myself, the Punto which replaced it was a much nicer drive.

Herself's Pride was one of the last batch, on a "V" plate. I understand that these weren't quite as good as the earlier ones, any other owners present and previous know why?

Oddly enough, despite Tom's comments above ours failed MOT due to extensive rust; possibly because of its location, spent much of its life in Aberwristwatch where there is a thriving colony of Kia Prides, think the local dealer bought a job lot!

Edited by Harleyman on 06/10/2009 at 14:41

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