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-   -   engine doesnt rev right (http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/166556-engine-doesnt-rev-right.html)

yousaidpoo 06-06-2004 08:29 PM

engine doesnt rev right
 
The car is a 1974 1.8 with L-jet:

The problems is after I have started the car (it usually starts ok, but if its been sitting for a day or two its a little tough) and its idling, if i tap the gas pedal, the engine is really hesitant to rev up at all. It will actually drop revs initially if i snap the throttle, but not enough to cut off. Also, if I rev the engine up very slowly, it runs rough around 2000-2500 rpm.

I recently checked the dwell and it was right smack in the middle of the "acceptable range". I'm thinking it may be valves, but I just checked them (last weekend and the car isnt even being driven outside of my neighborhood yet). If anybody has an idea whats causing this let me know.

Also, what color are the stock shock absorbers on a stock teener like mine? I got the car used from my aunt who doesn't have any records:rolleyes: and i don't know if mine is stock. The shock is a bright orange, and when i tried to clean it off the sticker with the brand name came off. There was yellow writing on the sticker if that helps. They also feel pretty stiff for what i would think would be a stock shock/spring package. I will try to post some pictures when I get a chance.

Dave at Pelican Parts 06-07-2004 07:25 AM

There were at least two different bright-orange shocks offered as aftermarket replacements for the 914. Koni makes or made some orange ones, and Mulholland did as well. Do a search on the latter name for at least a little info. The Konis seem to be more well-regarded around here, and I'm not even sure Mulholland is in business any more.

As to your drivability problem, I'd start by doing a compression check, and going through the rest of the ignition system very thoroughly. Then I'd check every hose on the car, and replace any that are brittle, cracked, leaking, etc.

And make sure they're routed correctly. The 75 1.8 diagram here on our site is close, but not correct, for the vacuum hoses, and the 74 2.0 diagram should be close for the fuel hoses.

Then move on to the wiring. Check all of the wiring in the engine bay--make sure everything is plugged in securely, all connections are clean and tight (most especially the grounds at the upper rear crankcase seam), and no wires are brittle or cracked.

Then open up your Haynes book to the Fuel System chapter and look through the L-jetronic component tests. Most can be done with an ohmmeter and regular hand tools. Try them. Also look through http://www.type2.com , as the later Buses also used L-jetronic FI, so their tech articles will apply reasonably well to you.

--DD

yousaidpoo 06-07-2004 10:38 AM

thanks dave, I've done most of that (recently replaced every inch of hose on the car, and checked compression)

I'll check for any wiring faults.

After looking at the schocks, I'm reasonably sure they are konis. Regardless, I'm leaving them in becuase they are nice and stiff.

One more thing... anybody know how to get out some oil that leaked onto the exhaust and got between the heat exchangers and the exhaust pipes themselves. Is there a way to get the exchangers off, short of cutting them with and oxyacetylene (sp) torch?

lmcchesney 06-07-2004 12:35 PM

Koni Special D's are bright orange. They have the adjustable gas shock compoent. The stiffness is changed via a fitting at the top of the shock.
L. McC

Dave at Pelican Parts 06-07-2004 04:04 PM

The heat exchanger "wrapping" is, I think, held onto the pipes by having the lip around the two halves bent over. There may be welds as well.

The usual solution is to drive the car and let the oil burn off. It's less than entirely elegant... You can also remove the exchangers and soak them in solvent for a while...

The other thing to check is your fuel pressure. A partially-blocked fuel supply will give you similar symptoms, so if the pressure drops off as the RPMs climb, that would show a delivery problem.

You can (and should!) also inspect for kinked fuel lines, particularly everywhere "upstream" of the fuel pump. And check or replace the filter.

--DD

jamcleod 06-08-2004 05:04 AM

i was thinking about your rev problem... what if the advance is not working properly/sticking... how would that affect revving? it wouldn't have shown up in the dwell measurement....

yousaidpoo 06-15-2004 06:53 AM

got the engine to rev right. purrs like a kitten... on steroids. Turns out the wires in the cold start valve were switched :confused: and it was on when it should have been off and vice versa. Dont know how that one happened, but its fixed now and the engine will jump right off of idle if i even blow on the gas pedal.

Thanks for the help


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