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914World.com _ 914World Garage _ Intermittent miss

Posted by: billd Oct 20 2005, 07:41 PM

I recently finished restoring my stock D-jet EFI. The car mostly drives fine (once its warmed up - I have issues with the AAR. However from time to time the car bucks - losing power for a quarter second or so - and then continues normally. So far this never happens at WOT - only at part throttle. It happens at relatively low RPM - from about 2,400 to 3,500. I haven't experienced it above 3,500 RPM. Any ideas on what it could be?

Posted by: john rogers Oct 20 2005, 07:54 PM

Every couple of years I have to open the throttle position switch and clean it out well with spray electrical cleaner and the contact areas with an eraser and then throttle response smooths out.

Posted by: Cap'n Krusty Oct 20 2005, 08:03 PM

QUOTE (john rogers @ Oct 20 2005, 05:54 PM)
Every couple of years I have to open the throttle position switch and clean it out well with spray electrical cleaner and the contact areas with an eraser and then throttle response smooths out.

That would be the first place I looked. BTW, if the cleaning doesn't work (and BE VERY CAREFUL), new ones are available and they're not that expensive. The Cap'n

Posted by: billd Oct 20 2005, 09:33 PM

Thanks guys. I'll clean the throttle switch and see how it works.

Posted by: smg914 Oct 20 2005, 10:11 PM

If that doesn't work, it could be something as simple as bad ignition wires or maybe you need new spark plugs.

Posted by: 914GT Oct 20 2005, 10:25 PM

Maybe check to see if you have timing too advanced.

Posted by: BMartin914 Oct 20 2005, 10:55 PM

I have dealt with the same problem in the past.

The solution ended up being replacing the FI trigger point wires from the distributor. They were frayed so bad they were shorting or causing inconsistencies with the resistance.

Frayed wires at the MPS can cause a simililar problem.

But if you just restored the d-jet...

Posted by: bd1308 Oct 20 2005, 11:35 PM

if its the 74 model, I have one for uber cheap...brand new (but without box)

my grandmother bought it for a xmas gift.....but i ended up wrecking my 914.

b

Posted by: michelko Oct 21 2005, 02:04 AM

Had the same problem,
adjusting the Throttle position switch cured that.

My advice: clean it and adjust it to factory spec´s (idle switch 2 ° opening etc.)

Posted by: motorhead Oct 21 2005, 07:57 AM

mine had the same problem shortly after purchase. dead spot at mid throttle. the tps had a bad spot in the contacts. replaced the switch, adjusted to spec, haven't touched it in about 15 years. thinking back, it was probably the only easy thing I've ever done on the little beast.............

Posted by: billd Oct 21 2005, 08:35 AM

Its definitely the throttle switch. I removed the connector to the throttle switch and drove the car a bit. The problem is completely gone. It does hesitate a bit though.

I then pulled the switch off and cleaned it with electrical contact cleaner and an eraser. Replaced the switch and the problem is still there. I fear that the groove worn in the contacts is so deep that the flat spot I have can't be fixed by cleaning. Did someone say they have one cheap?