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rockabillyjay
Joined: 22 Apr 2016
Posts: 7
Location: Orange County CA
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 Posted: Thu Apr 28, 2016 3:16 am Post subject: 1980 Bogs under load |
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Ok..just looked at a 1980 924 turbo I may purchase. Some background on the car:
been sitting about 6 mos
95k miles
ran fine before it sat
starts and idles fine. revs fine.
under load it bogs down..just falls on its face.
If you shift early it gets up to speed, but any attempt at speed and it just bogs.
Turbo spins and his mechanic says its fine.
Any ideas from this limited info? I need a So Cal turbo guru..I'd hate to buy this and have it be a money pit.
Bad injector? Blocked exaust? Bad wastegate?
Last edited by rockabillyjay on Thu Apr 28, 2016 4:04 am; edited 1 time in total |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Thu Apr 28, 2016 3:50 am Post subject: Re: 1980 Bogs under load |
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starts and idles fine. revs fine.
under load it bogs down..just falls on its face.
If you shift early it gets up to speed, but any attempt at speed and it just bogs.
Boost/intake air leak? What does the exhaust look like when it bogs? Black?
Check the connection of the lower charge pipe where it connects to the turbo down beside the head, it should be solidly mounted.. Very common and results in just that..
I'd hate to buy this and have it be a money pit.
What is your definition of a money pit? You could easily put another $1k into it to sort it out..
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80 Turbo - Slightly Modified |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Thu Apr 28, 2016 4:00 am Post subject: |
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| Quote: | | Turbo spins and mechanic says it's fine. |
Really? Based on what? Has he had it out of the car? There is no way to determine with the turbo in situ the extent to which the inducer and exducer blades might be damaged. The turbo might spin, but that doesn't mean it's producing boost. And how exactly did you determine that the turbo is spinning??? The design of the recirculation valve on the compressor housing prevents direct visual inspection, so unless the exhaust downpipe was off and you observed the turbine spinning, I don't know how you'd determine this.
Agree with Fasteddie...first thing to do is track down any potential vacuum and boost leaks, but based on your description, I would be very suspicious that the turbo is in fact NOT fine. And, if it WAS out of the car, I would be very skeptical as to whether things got put back together correctly.
These are not mechanically challenging cars. If the mechanic can't figure out (or won't disclose) what's wrong with it, I'd seriously question his credentials -- or ethics -- as a mechanic.
Also, what is the correct year of the car? There wasn't a 1989 Turbo. I suspect you fat fingered it, and meant to type 1980, but it's important to know, as the 1981-2 had several distinct differences which will be important for us to know to help you isolate the potential problem.
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erstwhile owner of just about every 924 variant ever made |
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rockabillyjay
Joined: 22 Apr 2016
Posts: 7
Location: Orange County CA
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| Posted: Thu Apr 28, 2016 4:18 am Post subject: |
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Curse these fat fingers! yes, it's a 1980
The turbo spins is all I was told
does the old "spray brake clean and listen for the idle to go up" trick work on these while looking for vacuum leaks?
I didn't check the exhaust when it bogs as it only does it while driving..and I was driving
$1k to sort it out wouldn't be money pit status in my opinion..but getting there! ha |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Thu Apr 28, 2016 4:45 am Post subject: |
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| rockabillyjay wrote: |
does the old "spray brake clean and listen for the idle to go up" trick work on these while looking for vacuum leaks?
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Yes but the lower charge pipe connection I'm talking about seals fine under vacuum (not on the vac side of the TB) but under boost pressure the pressure pushes the connection open and pressurized air gets out..
Many things can seal better under vacuum when they are being pulled together as oppose to boost when they are being pushed apart..
The amount of air is measured at the very beginning of the intake path for the injection system to provide fuel accordingly. Any leak where air escapes after the measurement does not go into the engine but it still provides fuel for all that lost air resulting in a very much too rich mixture, falls on its face..
The suspect connection I'm talking about is where 22 (lower charge pipe) meets 43 (turbo) if bracket 26 is not doing its job.. Boost pressure will make it lift off and leak..
If you can grab 15 (upper charge pipe) it should be quite firm and you should not be able to lift the left side of it at all..
Not saying that this definitely IS your problem but a very high probability IMO and will result in your exact symptoms..
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80 Turbo - Slightly Modified |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Thu Apr 28, 2016 4:57 am Post subject: |
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Loose lower charge tube doesn't cause bogging. It causes rapid bucking as the charge tube lifts off and resettles onto the compressor outlet in rapid succession as boost builds, lifts the charge tube, and then leaks out, allowing the charge tube to resettle. One would never confuse that behavior with bogging...it'll put your head thru the windshield!
Do you have a way to hook up a vac/boost gauge? This way you could tell if you were getting any boost pressure under load, while simultaneously checking for healthy vac at idle, which should be pulling a steady -20 to -16 Hg once the engine is warmed up.
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erstwhile owner of just about every 924 variant ever made |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Thu Apr 28, 2016 5:50 am Post subject: |
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When it happened on mine it was just a loss of power when boost came on bogging super rich..
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rockabillyjay
Joined: 22 Apr 2016
Posts: 7
Location: Orange County CA
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| Posted: Fri Apr 29, 2016 4:46 am Post subject: |
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It actually seems to bog before the turbo should kick on..
Checked to see if the Cat was blocked and it wasn't |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Fri Apr 29, 2016 6:38 am Post subject: |
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Again, this is indicative of non-functioning turbo. However, it's possible the car is running over rich. Many "mechanics" not familiar with the CIS system will futz with the fuel mixture in an attempt to fix a poor running car, only making matters worse. Any noticeable raw fuel smell when bogging? The cause for this could be a wide variety of faults in the CIS system, including leaking injectors, bad warm-up regulator, failed components within the fuel distributor.
It's really hard to tell from the description "bog" what might be wrong. But if I picked up the car, I would start first by trying to determine if there's any boost at all. If there is boost, even marginally, I would then focus on troubleshooting the fuel delivery system. Neither of these are cheap or easy repairs, so this might not be your best candidate for acquiring even if the cost of entry is low.
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Grenadiers
Joined: 20 Feb 2007
Posts: 3222
Location: Nelson, WI & Prescott, AZ
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| Posted: Fri Apr 29, 2016 7:10 am Post subject: |
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I think the collective needs a better idea of what you mean by 'bogging down'. In my mind, hitting the skinny pedal and nothing happens, in any car, (you hear it 'bogging') and it bogs down, could mean nothing happens until you feather the throttle for the engine to take. If so, in this car, it might mean a stuck CIS distributor plunger that is covered in varnish and reacts slowly to the skinny pedal. Just one of a multitude of problems in a 36 year old CIS car!
If you are mechanical, the car is in great shape for it's age, and you really want it, and think you can fix it, buy it! You'll probably not figure this out before you buy it. yo.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
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2014 Kia Soul
2001 Ford F350 powerstroke |
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