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Autobahn Garage
 
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Unhappy No power 914

I have a 1970 914 in the shop. The engine was rebulit w/ a new cam shaft,and new heads. Here is the problem. I have checked everything over again and again, the timing, valve clearance, and fuel presure. The car will idle very good, and rev o.k. but it has no power. You have a hard time getting up to 55 and it serges. I have rebuilt many engines before so I'm sure it's nothing internal. I think It's in the fuel injection system? But where? I have replaced all the vacuum hoses, cap,rotor,plugs,points,condensor,wires,filters,tem psensor on the head,manifold presure sensor,injector seals,coil. Aiso all the ground's have been cleaned,This car is haunting me. I have not changed the trigger points? I just don't want to keep putting parts on If It's not going to fix the problem.Any idea's????? Please help me I'm losing my mind with this car. THANKS GUY's TAB
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Old 09-29-2003, 11:37 PM
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Did you put these new parts on in preventative mainenance or did you put them on after your problem? If it's preventative mainenance I'd start putting the old parts back on and see if maybe any of the new parts were faulty.
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Old 09-30-2003, 05:39 AM
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What cam did you put in? What heads? Did you change the pistons?

Geoff
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Old 09-30-2003, 06:53 AM
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First, I replaced the parts as needed, all the tune up parts. I have went back and put the old parts on one at a time, with no change in preformance.The cam shaft is an Elgin stock grind, It should work just fine with the injection It's not a radical race cam.The pistons are the stock one's.And the heads are rebuilt w/ new guides and valve grind they were also fly cut to give a new gasket surface.Will the trigger points cause this problem??????
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Old 09-30-2003, 07:06 AM
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I had a similar problem once. When I checked the timing, I noticed the advance wasn't working--the fly weights in the distributor had enough corrosion to freeze them in place and prevent the timing from advancing. The symptom of the problem was low power.
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Old 09-30-2003, 07:14 AM
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Did you test the injectors and set the fuel pressure gauge?
Old 09-30-2003, 07:48 AM
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Did you check/set the fuel pressure, and did you pull the injectors and test them. I've had 914's that stumbled and lacked power. I put a new sent of injectors in and the car ran like new.

Regards,
Daris
Old 09-30-2003, 07:50 AM
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I don't want to step on tabs toes but the Elgin cam was a performance grind and the heads are 1.8's originally 1.7's were in the car. (I only know this cause it's my car) I don't know if this make any dif. but i figure as much info can't hurt. tab is right we both are losing are minds with this problem!!! any ideas are gladly welcome!!! thanks Rob
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Old 09-30-2003, 02:49 PM
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What kind of "performance grind"?? Some of them play very poorly with the stock FI...

--DD
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Old 09-30-2003, 03:37 PM
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it came from PAP-Parts here is a quote from there online catalog. ----

914 Performance Camshaft

Porsche 914 1970-76 and VW Type 4 Camshaft with mild performance grind for fuel injected cars to no emission control specifications. $25 core charge

sounds like it should be ok??? am i wrong and if so is a carb the answer?
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Old 09-30-2003, 05:02 PM
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Cam Timing? Test fuel lines for flow? Battery Voltage when running? Steve
Old 09-30-2003, 06:49 PM
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Ok, now it has stock 1.8 heads and the pistons are the 1.7 ones?? How did you make that work?

Even a mild preformace cam will run with Djet, it just doesn't idle very well.

What did you set the compression ratio to?

If you mix and match parts you can come up with a low compression low power motor pretty fast....
Geoff
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Old 09-30-2003, 06:52 PM
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Do you know for sure it's running on all 4 cyls, not just two? I"ve had 4's that were running on opposite 2 cyls and it seemed smooth, but no power. Trigger contacts might cause this.

Spark advance not working would definetly cause lack of power.

Any unusual noises, smoke, etc coming from the car?

What do the spark plugs look like?

What are compression readings?

Bleyseng's right, 1.8 heads won't fit properly onto the barrels of the 1.7 cyls, since they are a larger diameter. something may be amiss there.
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Old 10-01-2003, 06:59 AM
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Please take the following suggestions in the helpful manner they were intended and dont get offended if I state the obvious, this is what I would do:

Go after it in steps. Testing will tell you everything if done right and in a logical sequence.

first, check compression on all 4 cylinders to make sure they are in spec. you can't fix the ignition or fuel injection if the problem is mechanical. Even if you know that isn't the problem that information provides a useful baseline later on and should be done on all rebuilds and isn't that hard to do.

Then diagnose the ignition system. Make sure you have spark to all 4 wires at idle. you can do this with a timing light. Check all grounds related to the engine, they can mess with your head to no end.

Recheck the firing order. I know, I know, but I've been working on engines for 30 years and I've got em wrong before, only to find it after too many curse words.

Then pull and inspect the plugs for clues. If one or two are wet there's you answer. If they all are dry look at the color.
If all 4 plugs look like they should, Inspect the distributor for excess wear or sticking. Pull a vacuum on the pot and see if the advance or retard plate moves. wiggle the shaft to see if if has a lot of slop.

Then take the car up to 55 or as close to it as you can. Whatever it takes to run for a few seconds at full throttle.
Find a spot where you can pull over. Cut the ignition off without letting off of the throttle and push in the clutch at the same time. Pull the plugs again. if you find anything unusual let us know and we will help diagnose it.

If everything looks good you can progress to the fuel injection system.
Like they said, fuel pressure is first. What pressure did you get? Do you have a way to read it at full throttle to see if you have a fuel supply problem like a weak pump, clogged filter or kinked fuel line?

Next pull the injectors and put them in suitable containers (remembering that the fuel is flammable and you need to take approriate safety measures).

Another test is manifold vacuum. Very helpful test that one is.
After than we can get to testing the cylinder head temperature sender and some other tests.
I've done the shotgun approach before, changing parts in hope of getting lucky. Most of the time I wasn't.

gather all the information you can through testing. that will point you in the right direction or the information will help us direct you. It is a very valuable learning excersise. it will also save you money most of the time and reduce the frustration level.
I don't really mind fixing a problem no matter how much of a PITA it is. What I absolutely hate is not knowing what is wrong or how to find it.
Old 10-01-2003, 07:50 AM
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The distributor advance is working, I checked the compression It is with in spec, The head s were fly cut to fit the 1.7 cyls I will do another compression check just to be sure!!! How can you check the trigger points ??? They are clean and have not sign of wear??There is no smoke for the car it starts right up. The plugs look like they are firing but I have not ran it long enought to see if the mixture is O.K. It's not running rich. It just has no power The battery voltage is 13.7 when the car is running.Also the fuel pressure is set to the spec psi.Thanks for all the help guys
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Old 10-01-2003, 07:57 AM
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Good advice Sammy.

One other test I find useful is a balance test- pulling a spark plug wire one at a time off at the distributor end and noting how much the engine speed drops. If it's firing on all cylinders properly, it will drop the same for each plug. If the engine speed doesn't change, that cylinder isn't firing. You can also do that on Djet by pulling the injector plug out.

don't do that at the spark plug end unless you want to get zapped!

a side benefit of that test is that as you pull the wire, the gap gets wider and the spark get's "hotter", sometimes firing a plug which is fouled otherwise. You'll here the cylinder "kick in", and out again when you put the wire back into the cap.

Once you know which cyl's aren't firing all that's left is to find out why.

In my experiences with trigger points, they wear down the block which rubs on the cams, and don't fully open. each side is supposed to be open for 180deg rotation of the distributor, and closed for 180. check with an ohmeter connection to the middle terminal and one of the side terminals, then the other. If you need to, you can bend back the contacted terminal slightly to increase the gap, but don't do that unless you're sure they've been worn awhile, because you can't "regap" them.

Murphy's law would say if you replaced everything but the contact points, the problem is the contact points. ;-)
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Old 10-01-2003, 06:25 PM
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We found the problem, bad injectors on #1 #3 I let you know how it runs after we get the parts. Thanks to all you guys who helped me with this
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Old 10-02-2003, 05:13 PM
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Hi Tab,

Saw your post on PelicanParts and you seem
to be reliving my nightmare from awhile back.

I spent a couple years piecing together a new
2L engine to replace the tired 1.8 in my 914.
Tried to adapt the L-Jetronic but that's another
story. Took another year to get the D-Jetronic
going with rebuilt injectors. Ran great for a
week before it started surging. Traced it to
the injectors and bought $500 of new ones.
Ran great, for a week then started surging
again... Rather than blow another $500 on
injectors I rigged a brake vaccum pump and a
power supply (to open the injector) and
"backflowed" them to clean them and found a
lot of "crap" was plugging them. In short I
found the garbage Fram fuel filter I recently
replaced didn't seal along the sides and was
allowing bit's of rust and garbage to get by.
Replaced it with an OEM filter and put another
steel inline filter in the engine compartment
as a backup. Not a problem since.

Just took it out for a drive and the funny
looking little car never fails to impress me.

Regards,
- Mark Lakomski

75' 914 2.0L
65' Mustang
86' ZX1000R
90' Rustbucket S10 transportation

-----------------------------------

We found the problem, bad injectors on #1 #3
I let you know how it runs after we get the
parts. Thanks to all you guys who helped me
with this
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Old 10-19-2003, 01:38 PM
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bad injectors on 1 and 3 hmmmmm, sounds like trigger points or a bad connection.wiring to the injectors....Injectors simply do not fail in pairs....
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Old 10-19-2003, 01:50 PM
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I'd go with F.I. points. You can't go wrong. If they have over 30k it's time anyway. On the other hand, I have experienced similar haunting problems before myself - last year. Turned out that the F.I. harness was toasted. Thirty years old; insulation was brittle & missing in some places. Replaced the harness with a rebuild from Bowlsby (this bbs). Problem resolved & it idles like a champ. Nice bonus! It never idled steady before. Always wandering...
Check your harness for arcing/shorting. Good Luck!
It's all worth the effort.
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Old 10-19-2003, 02:14 PM
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