extanker

you need a scan tool [at least snap on,s latest] not a code reader and a pro repair manual. just a check...when you have plugs out do a compression check....if your chain timing is off you may see very low compression.

Duezzer

I will check the compression but really don't suspect it is an issue as I have been able to get the car to fire on occasion. It drove like a dream. Pulled hard and ran very smooth - and all cylinders were the about same temp. Within +/- 5 Deg C. Checked them when we pulled it into the garage when it started to act up again in the driveway.

Car has a tough time starting. Sometimes it will catch and run nice. If you slowly (slip) let the clutch out and let the motor try to pull the car it just shuts off. Like you turned off the switch. Then it becomes really tough to start. Basically foot to the floor till it fires up. If you keep the revs up just a little bit you can keep it running and it runs very smooth - It is not snorting or coughing or chugging - just shuts off. Full out quits.
I have the plugs out of it right now making sure the cylinders dry out but before I put them in I will check compression.
I wish I could afford a scanner like you have suggested above but that is not in the cards right now.
The best I got to work with is a INNOVA 3100 CAN/OBDII Code Reader

Gerald Finden

Sounds like a problem I had with water in the gas. Water settles at the bottom of the tank and that's where the fuel pump is pulling from. When you check your plugs they smell enough like gas to not detect water. Once your gas has settled, say, overnight, pump out a couple of gallons. Problem go away? Just a thought.

Macster

I don't think a compression test at this time is called for.

I don't think timing has jumped based on the fact some cylinders on a bank appear to be working/firing just fine (their exhaust runners are hot) while others on that same bank are not (their exhaust runners are cold).

The fact when you removed the plugs of the "dead" make that cold cylinders the plugs were wet with gasoline suggests to me the problem is some cylinders are not getting spark.

This then suggests a wiring problem. The reoccurring crankshaft position sensor error reinforces this. As I read it then sometimes the engine runs just fine on all cylinders further suggests a wiring problem, but unfortunately an intermittent one. Bummer.

Then this suggests the problem is further up the line, well, make that wire.

You have to check the engine wiring harness from from right at the coils all the way back to the DME and then you have to check the DME.

Look for a loose/damaged connector. Check for any signs of wire abrasion, or that the wiring has been pinched or crushed, or has been chewed by rodents.

At the DME check for any signs of DME or its circuit board being subjected to moisture.

Caution: Mind static electricity. Remember all wires, all pins/sockets in each engine compartment wiring harness connector leads back to the DME. Static discharge into one of these and you can fry the DME. Actually you probably won't fry the thing, you'll just zap an input or an output and then you'll have another puzzling error or symptom to add to the mix.

On a related note be sure the battery is good and all the cabling/connections from the battery to the car/electrics are good.

When the engine is acting up and when it is not it might be of some value to check the battery voltage looking for possible an intermittently underperforming alternator.

Duezzer

Update.

Compression Test - all cylinders good - within spec
No water in fuel
Fuel Pressure withing spec
Put Bosch #7 plug back in
Car turns over and tries to fire but wont.
Has previously fired up and ran great above 800 RPM on the tach
Grabbed a can of starting fluid - sprayed a very very small amount in the intake.
Car fired up nicely - as soon as foot was taken off throttle peddle car would die
Had friend check for vacuum leaks using the ether all over the engine compartment while I kept the car idling at 1500-1800 rpm
No Vacuum Leaks found
Thought we may have an issue with the Throttle Position Sensor.
Pulled of what we thought was the TPS and then realized hey!!!! That isn't the TPS - Looks threw manual and found the car also has an idle control valve - (ICV)
Pulled the ICV and took a look at it - very dirty inside - cleaned it up with sensor cleaner - Installed it back on the car and it almost started - way better than any other attempts.
For ****s and giggles tried the car with the ICV plugged in and not plugged in.
Car reacted the same both ways. Did it 3 times to confirm.
Needed a small shot of ether to fire up - would run above 800 rpm with just a bit of throttle with or without the ICV

Our suspicion is that the ICV has failed and this is our hard start issue.

Any thoughts? Besides - OMG I would NEVER EVER use ether on MY CAR!!!!

What controllers the ICV and I suspect there is a test procedure for the ICV.
Read on line that someone had cleaned their ICV up and did all the tests suggested (passed all) and it still would not work. Replaced it with a friends they knew was good and car fired right up.

So I am leery of doing a bunch of tests on it for not. Does the TPS activate the ICV? Can this be an TPS issue?

Thanks for all the help and suggestions so far.

Duezzer

Macster

The TPS doesn't control the ICV. This is done by the DME to control idle speed.

If you replaced the ICV with a known good ICV from another engine and the symptom/behavior went away and the engine fired right up I'd say the ICV is the source of the behavior you been dealing with.

In a later post I did mention the ICV, they can get dirty and require cleaning or they can just go bad.

Of course there was a lot of other stuff mentioned too. Part of the problem on my end is you were describing the behavior as if the engine were being flooded and this instantly caused me to suspect a fuel supply/pressure problem.

However, if the ICV isn't working right then the engine withers gets too much air at idle and spits back through the intake and possibly stalls or it gets too little air and back fires through the exhaust and possibly stalls.

While I do not know of any ICV tests -- generally they have just been replaced if suspected -- a search turned up this:

Hook up the power probe to a 12v power source such as your car body. Attach a alligator clamp jumper to the ground on the Power Probe (yellow) and another jumper to the needle of the power probe (red). Give the inside of the ICV a good cleaning. I sprayed carburetor cleaner first for cleaning, then WD-40 for lubrication.

There are three terminals on the ICV. The center terminal is positive, so attach the positive lead to this terminal. The two outside terminals are ground. The ICV works by swapping ground rather than swapping positive electricity.


Attach the positive jumper to the middle terminal, and the ground jumper to the top terminal. Give 12 volts to the ICV either by pushing the button on a Power Probe, or whatever archaic method you wish to use.


This should close the ICV.


Swap the ground jumper to the bottom terminal. Once again, give the ICV 12 volts.


This should open the ICV.


The action should be quick and snappy

Gerald Finden

Take a look at what Barry Waters went through: https://rennlist.com/forums/911-foru...lem-cured.html

Our ICV was cracked on our '99 Boxster. Symptoms; hard starting when warm, CEL lit up on hard acceleration, erratic idle. Fixed it with Q-Bond months ago. No problems since.

Duezzer

Well I guess I am now looking for an Idle control valve to test out the above therory.

Tried Cleaning and lubercating the one I have and still does not function properly.

These are the part #s

Bosch Part # 0 280 140 572
Porsche Part # 996 606 160 01

If you have a spare please let me know and we can work out a deal

Thanks,

Duezzer

flyingpenguin

Did you actually take the two halves of the ICV apart? If you pry out the pin holding them together you can open the assembly for a really good cleaning. Worked for me.
I have a refurb lying around that is confirmed to work.

Duezzer

Mr. Penguin,

Did not know it came apart like that. I will give that a whirl.

Thanks for the tip.

Any idea what the output to the ICV should be reading during start up - I would like to make sure it is getting the propper signal and I don't have an issue upstream in the control system.

If this does not work - I will send you a PM and we can discuss the refurb you have.

Again - Appreciate the Help.

Duezzer

Duezzer

Pulled the Idle Control Valve today - Could not figure out how to get it apart for a more thorough cleaning - Since this was a dead end for me I did a bit of investigation - Put Positive 12V to middle pin on Valve electrical connector and Neg to left and right side - Valve opened and closed nicely.

Then checked connector on car - With car ignition on - but not running I get voltage on both sides of the connector. I connected the ICV back up electrically and watched what it would do. All it did was buzz - as in - the motor was powered up but the valve stayed stagnate and did not change position.

I would of suspected that there would only be power to one side of the valve to open it up and then close and open as required to keep the car running.

I am not sure if I am missing some information on how this valve works, My thought was the valve would open fully at start to get the air in past the butterfly valve in the throttle body then close down or open up as needed - I did not expect what I found.

I am sure the idle issue with the car related to the Idle Control Valve - or the control of the valve.

Anyone have any ideas or tests I can run please let me know.

Thanks

Duezzer

extanker

auto repair info 101................not all the little gizzmos on a car with an ECM are powered by 12 volt. without the proper test equipment and manuals you are going to make matters worse.many of the experts here are truly trying to help but are clueless. FLATBED IT TO A KNOWN GOOD REPAIR SHOP before you fry something looking for a rat.