D-Jet Issues-getting close, Need a little more specific advice |
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D-Jet Issues-getting close, Need a little more specific advice |
OU8AVW |
Mar 16 2015, 09:17 AM
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#1
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Yacht Rigger Group: Members Posts: 1,803 Joined: 1-October 08 From: Granbury, TX Member No.: 9,601 Region Association: Southwest Region |
So I got my car back from the local Porsche shop and installed a rebuilt MPS from Bowlsby but the car is still not running right. Flat spots and intermittent dead fire misses. She starts right up, idles well and drives ok but when you get on it it has intermittent flat spots and when shes just cruising it misses once and a while. Seems like the advance is not ramping up like it should. Also, the mechanic left a vacuum line off the distributor. The line from the inboard connection on the pot is hooked up but the outside one is off. I understand that one of these is advance and one is retard.
Just need a list of crap to check (IMG:style_emoticons/default/biggrin.gif) |
OU8AVW |
Apr 23 2015, 07:41 AM
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#2
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Yacht Rigger Group: Members Posts: 1,803 Joined: 1-October 08 From: Granbury, TX Member No.: 9,601 Region Association: Southwest Region |
So now she's running pretty sweet. I am hiving a high idle issue. It idles at around 1600 rpm. It feels like the adjustment screw on the intake is mostly all the way in and I get no change from turning the adjuster on the computer. I checked for vacuum leaks with map gas but found nothing. I'm going to fiddle with the TPS some more.
Any other ideas? Maybe check the timing again? Maybe the advance is sticky? (IMG:style_emoticons/default/blink.gif) |
worn |
Apr 23 2015, 11:00 AM
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#3
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
So now she's running pretty sweet. I am hiving a high idle issue. It idles at around 1600 rpm. It feels like the adjustment screw on the intake is mostly all the way in and I get no change from turning the adjuster on the computer. I checked for vacuum leaks with map gas but found nothing. I'm going to fiddle with the TPS some more. Any other ideas? Maybe check the timing again? Maybe the advance is sticky? (IMG:style_emoticons/default/blink.gif) High RPM is almost always a vacuum leak. There are so many hoses it is hard to find them sometimes. With your car I would suggest that you install an A/F meter and place the gauge where you can see it as you drive, rather than down low like one idiot I know personally did. The original MPS settings aren't going to be quite right and after you mess with the car it will need some adjustments. I also added a CHT sensor and found that when it is running well close to lambda = 1 at around 14 the heads are heading towards the recycling bin. Richening the mixture has cooled them and there is a sweet spot where the mixture is around 12 most of the time and a bit leaner at idle. I know that the gauges are expensive and a pita to install. Especially the bung in the exhaust. But as you say you built it from scratch so you know your way around the block. I have to add that I am running the resistor from the 1973 model to richen the mixture by fooling the ECU into thinking the car is still a bit cold. Sounds like you have a really nice engine there. Good luck! |
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