What's causing a 3200 idle in my 2.0L?

[A/SP911]

I just reinstalled the engine on my 2.0L 1973 914 after sending it out to have the heads freshend up and it now idles at 3,200. Playing with the timing only makes it go faster.

Did I get some hoses mixed up when I replaced them with new ones?

Did the engine shop get the distributor off by one cog?

Is something wrong with my cold start valve? AAR valve?

Thanks
S.Chapman
1973 2.0L 914
1980 3.0L 911

[RandyLok]

Major vacuum leak most likely. Not cold start valve. Could be AAR, plug the hose to find out. Look at all vacuum hoses that connect BELOW the throttle body butterfly.

[galto]

Also check your idle screw. Don't trust lines completely, make sure they don't have any pin prick holes.

[Dave at Pelican Parts]

Look for a large hose connected from "upstream" of the throttle body to the manifold, with no "component" in the middle. There should be no hose that makes this direct connection; if you find one you have found the source of your vacuum leak.

Also check for fittings on the manifold that do not have hoses attached to them.

--DD

[914fan]

I had this problem one time. If you are running FI or breather hoses to your carbs check this out.
On the passenger side of the fan shroud there is an outlet to feed air into the gas tank charcole canister. IF you hook that port to your FI anywhere (except the factory location in the air cleaner) you eliminate your vacume and cause a very high idle. The same would be true if you hooked that hose up to the top of your carbs, or to your valve covers and then to your carbs. Also did you check that your throtle is closed? Sounds silly but it could be stuck slightly open.

[A/SP911]

Awesome info guys! I appreciate the help! There is not many P-car mechanics up in these parts.

I'm painting the car (Gulf racing colors) tonight and tomorrow so I won't be able to get to the engine until the Weekend ...but I'll let you know how I make out.

Thanks
S.Chapman
1973 C/S 2.0L 914
1980 A/SP 3.0L 911

[A/SP911]

I still haven't found the problem... But I haven't been able to spend much time at it as the painting is taking me longer than expected.

I did put in some cheap injector seals that looked more like a big rubber washers than the form fitting boot that came off. Could this be my problem?

Thanks
S.Chapman
1973 C/S 2.0L 914
1980 A/SP 3.0L

[Dave at Pelican Parts]

Form-fitting boot? That doesn't sound familiar to me. The inner (small) injector seals are fat rubber washers. The OD fits into the recess in the head, the ID fits the injector's pintle cover.

Check your hoses versus the hose diagrams available elsewhere on this site.

--DD

[galto]

That 'form fitting boot' on the lower injector is a worn out seal. You would be flat and squished if you were clamped down and heated up too. Anyway, a vacume leak could have been hiding other probolems if now everything works OK.

[A/SP911]

It was the rubber hoses that hold the intake runners on the throttle body... they were sucking air!

I was concentrating my search on the vacuum hoses for the last couple of weeks and never even thought about checking these hoses until last night. I put a clamp on them and the idle settled down.

I might still have a problem with my cold start valve though as it seems to run better with it unplugged. I'll do some reading on this board and see what may be up with that next.

Thanks for your help!

S.Chapman

[w9r1]

bad injector seals or bad intake manifold seals?

[RandyLok]

Originally posted by w9r1
bad injector seals or bad intake manifold seals?

Huh? That last post musta snuck in under ya.

:hijack: w9r1, very nice ride btw. :/hijack:

[A/SP911]

The new injector seals were OK. The old ones were so worn out that they change shape as Galto pointed out.

The problem was with the braided hose that connects the intake runners to the manifold.
I covered the braided hose with heat shrink to try and dress it up a bit. Maybe the heat shrink did something to it? So now it has eight ugly hose clamps holding it in place

I did have to ground out the head temperature sensor to get it to run right. It's only used in Solo II events so the day to day drivabilty isn't an issue but it does bring up another question though... Does bypassing the sensor affect performance?

BTW I mentioned earlier I painted it Gulf colours. Here is a link to pictures of the car, Enjoy!
Pics of my Gulf Racing coloured 914, Tell me what you think..

S.Chapman
1973 C/S 2.0L 914
1980 A/SP 3.0L 911

[Bleyseng]

geez, new manifold to plenum boots are cheap! You shouldn't have to cover them if they are new. Change them out and when you do center them somewhat so they seal.

grounding out the CHT means you are richen the mix to cover up your lean condition from the air leaks.

fix em before you burn a valve.

[A/SP911]

I reused the old plenum boots as they looked OK and covered them with heat shrink for what I thought was some extra protection. My next order with Pelican parts will probably include them.

grounding out the CHT means you are richen the mix to cover up your lean condition from the air leaks.

The vacuum leaks are gone so that isn't a problem anymore.

What seems to be a totally unrelated problem was a miss under acceleration and some black and white smoke. So I had the injectors calibrated, set the fuel pressure at 32psi, and disconnected the cold start. When this didn't help I grounded out the sensor and it worked much better. Yes, cold start is hard ..but it is used only for competition.

My understanding was that (besides telling the cold start valve what to do) the temperature sensor richen's the mixture to the injectors and grounding it out would stop it from doing this. Am I wrong on this?

Thanks
S.Chapman

[galto]

http://www.ratwell.com/technical/TempSensorII.html

some good info on the Temp Sensor II.

It's to give the ECU an idea on what temp you are running at. Shorting it out would be a bad idea. I don't know how bosch decided to deal with fault modes. Basicly, the could have set it up to run in a full lean condition (as the circut behaves normaly)
As the temp increses, the resistance decreses thus in a leaner condition, but if there is a dead short (Should never happen) they could have put it into a limp-home mode by using a comparitor to drive the input for the injector additional duration high.
Anyway, don't think shorting it out is a good idea. At the very least, you should get the avg temp the engine should be working around then put a resistor of that value in the circut. It will run too lean at statup, but should behave normaly once up to temp. The air plenums should be very tight. I remember replacing mine and having much fustration.

[hardflex]

hey Bleyseng, how do you like the Raby Cam with your Djet? Work good?

[Dave at Pelican Parts]

Shorting out the HTS makes the EFI run as if the engine were very hot--full lean! You richened up the mixture by running the fuel pressure up to 32 PSI, and leaned it out some by grounding the HTS. The car will likely run like crappola until the engine is fully warmed up, ~5-10 minutes.

Try dropping the fuel pressure to the spec of 29 PSI (2 Bar even, if you've got metric gauges), and see if hooking up the HTS will let the car run right.

Unplugging the HTS (not shorting it to ground) makes the mixture very rich.

--DD

[A/SP911]

Thanks again guys!

I don't know where I got that 32psi figure from. I checked my notes again and it is set at the correct 29psi.

Just before I go out and buy a new sensor, is there anything else that could be causing my problems? To recap... by grounding the sensor my power is up, the hesitation is gone, the white smoke is gone, and their only seems to be a small amount of black smoke when revving it up now. Oh, and my cold start sprayed continously before I grounded the sensor and I had to unplug it to get it running.

Also I don't know if this comes into play or not but when the garage put the heads back on they got them mixed up and I had to splice in a longer piece of wire to get it to reach the other side of the engine. (You can see the wire running between the drivers side intakes in my picture)

Dave, BTW that olympic blue car of yours looks awfully close to gulf blue in colour. I think you should run a big orange strip down the middle

Thanks
S.Chapman

[hardflex]

Remember, the cold start valve should open only at below Freezing temps, and should close again after the engine is warm, so it really shouldn't be an issue at all, IMHO, unless it's leaking. I would disconnect the fuel supply from the CSV and connect the CHT back up to see if that makes a difference. If it doesn, the CSV is leaking. If it doesn't, then I'd check the MPS to see if it holds vacuum.


It might run better now for you, but it's still not right, and when it's not right, your engine wear and chance for failure is higher. I'd make sure it's right. Nothing like it when it's all correct.