Hesitation on 2.0L

[retro74]

This is a followup from a prior post.

My stock 914 2.0L has now had:
-All new vacuum and air line hoses
-New Intake runner hoses
-New Intake runner to head gaskets
-New Throttle Body Gasket
-New Cold Start Valve Gaskets
-New Injector rubber seals (both)
-Throttle Body was cleaned up
-Air Dist was cleaned up and painted with POR-15
-New Plugs, Bosch Wires, Cap, Rotor
-New Points and Condensor
-New Bosch Blue Coil (old one had a crack in the side and was so old that the blue was fading away after 250,000 miles).
-Dwell set at 48 degrees (holds), timing set to 27.5 degree mark at 3,500 RPMs
-Distrubutor cleaned-up inside
-Idle switch set to spec (1 click past 0 Ohms)
-FI points are only 20,000 miles old and look good
-Aux Air Valve works fine and rotates fully after @ 5 minutes. Also, no vacuum pressure when my thumb covers this valve when engine is warmed.
-Cold Start injector works, but is not enabled since my Thermotime Sensor has been disconnected until I get a working replacement. This only affects the firing of the cold start injector.

I used a vaccuum gauge on decel valve hose and it holds steady at all rpm's and vacuum builds steadily as rpm's increase (nice!)

I used a vacuum gauge on my one vacuum advance line and it generates positive pressure and not vacuum pressure? Idle speed increases when hose is disconnected.

Engine is running strong now and I can accelerate in 4th going up hills - feels nice. Idle screw was gunked-up and when I cleaned the throttle body, I cleaned out the idle circuit with alcohol and a Q tip.

NOW... Off the line from 900 rpm idle, it hesitates. When I "blip" the throttle, the engine still hesitates, even after all of this work?

What test procedure do I check next?
By the way, it just keeps getting stronger as I find more little tricks...What about the idle speed adjuster on the ECU?

As always, thanks in advance.

Joe

FOLLOWUP:
9/7/01 Just got my new Cylinder Head Temp (CHT) sensor from PP and I installed it in 1 hour flat (see

Old CHT was reading almost 2000 ohms at 75 degrees F, but stayed close to that reading when warm. Symptoms of promblems were as follows:

- Bad fuel economy
- Hesitation from idle (too rich)
- No power off the line when fully warmed. It would stumble and make letting out the clutch a real chore at a traffic light (too rich)
- Cutoff completely when idling for too long since CHT got hotter and hotter with no air moving under car. I noticed this when I did the set the timing and it was idling for so long.
- Ohm meter reading was way too high on CHT.
- Adjusting ECU Idle to the left (lean) was all the way to the left because it got too rich to the right.

So I got a Fuel Pressure gauge ($39.00 from Sears - Cheaper than ebay with freight). I picked-up an old chrome wheel valve from a tire store on the way home from Sears - should have threads on both sides so that you can easily use this gauge on the 914 cold start injector line. Well, guess what? Fuel pressure was at 36psi! So I adjusted the pressure (counterclockwise for less) and it is not set at @ 29psi. Of course my lean ECU setting was now wrong and I turned the ECU adjuster to the right, to the middle to bring up the idle. Blip the throttle and NO hesitation! Full throttle is still fine. WOW!

By the way, the page reference below is AWESOME for D-Jet information. A must have, must bookmark page!

Thanks are in order to PP's bulletin board and for everyone that spends a little time making others smile.

Joe

[This message has been edited by retro74 (edited 09-09-2001).]

[Bleyseng]

You mention the timing is set but to what? Sounds like a timing problem to me, recheck that it is to 27 degrees BTDC at 3500rpm. Also check that the vaccum hose from the throttle body is hooked up to the retard fitting on the distributor (the back of the vaccum canister).
Geoff

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76 914 2.0L

[bowlsby]

Maybe too rich? Or lean? Have you checked the A/F mixture with a reliable gauge?

Do all FI components match? For instance you are not using a 74 ECU with a 73 MPS are you? All Fi parts must be from teh same system to work together properly.

Check it out here:

http://members.rennlist.com/pbanders/djetparts.htm

The idle adjust knob on the ECU adjusts the mixture at idle conditions only, otherwise it has no effect.

Oh, and the 'cold start valve' that you put your finger on the tube when its warm is the Aux Air Regulator. The cold start valve is the one with gas going to it...a '5th injector'.