Car fires without a problem, but idles quite rough, and runs very rich, so much so that when the it settles down to normal idles, it floods out. MPS was replaced with a used but tested one recently. When it was last running ( a year ago) it ran a little rich, but nothing like this.

As of now, the CHT is not connected. When it is connected, the RPMs jump up to 4000 and stay there. When the CHT is bypassed with direct grounding of the harness, the results are the same as with the sensor being disconnected.

I have no reason to suspect the injectors, FPR, Decel Valve, or the MPS.
Any and all advice is welcome.

-Todd

I thought the CHT had to be connected to run; must be mistaken. Start from the basics: valve adjust, dwell, timing, fuel pressure, vacuum leaks...

Running that rich makes me suspect the MPS (even though you say it has a tested one). Pull the vacuum hose off the MPS and see if that kills it. If it runs the same, the mps is bad or the vacuum hose to it is bad or incorrectly plumbed.

Disconnecting the CHT will send the mixture very rich. That's one problem. It sounds like that is masking a second problem. Make sure the CHT is in spec, hook it up, then try to determine what the other problem is.

--DD

I didn't think an open CHTS would allow the car to start either, I know if you disconnect it and ground the lead that goes to the brain (not the CHTS itself) it will fool the Brain into thinking the engine is warmed up fully and cure the rich running........if in fact the CHTS was causing the rich running....................Jerry

I had a CHT go bad. Went open when hot. Biatch to find. So yes, I think they will start. The air intake temp sensor will cause rich running to. I would check the throttle position sensor. Calibrate it per the specs.

I am working with drumsticks on this car and have done the following in the last 24 hrs to track down the source of this problem;
I replaced the vac. hose going to the MPS - there seemed to be good vaccum on the MPS end of the hose when running and connecting it to the MPS while running had minimal effect- still flooding out. At the same time I connected the hd temp sensor lead to the inj. harness lead which makes the eng race immediately without moving the throttle body flap.
ALSO - grounding the hd temp lead from the brain had NO effect.
I am beginning to think we are barking up the wrong tree. This car ran pretty good a year ago, albeit a little rich, without the hd temp sensor being hooked up.
In the process of restoring the car over the winter, we removed the throttle body and intake tubes for cleaning and painting and then re-assembled with new gaskets. No other EFI components were disturbed. The throttle valve sensor was recalibrated upon assembly. As stated before, the eng. fires right up but the plugs eventually drown in gasoline at idle.
I have not yet checked the fuel pressure - possible source of the problem?

We are frustrated and open to any and all advice.

CHAZT54

My advice,

I fought an intermittent rich condition for a long time...
I bought and installed a new CHT which was defective from Bosch.
I will always check new parts now before I install them.

Pull the CHT , test the resistance at cold & hot temperatures using your stove top and a pan of hot water.

Cold it should measure 2,000 to 3000 ohms.

Hot it should measure less than 1000 ohms.

Trust me the car will not run correct without this sensor functioning properly.

Did you actually test the MPS to see if it holds vaccume? 15lbs for 15mins I think. Do all the EFI parts numbers match up for that model year car? It's amazing what gets swapped out over the years.

http://members.rennlist.com/pbanders/DJetP...htm#Drivability this shows you all the part numbers and causes for fi issues. Good luck.

That's a big red flag to me! If the RPMs went over 2K or so, you have a vacuum leak. A pretty large one, in fact. Advanced timing can also raise your idle RPM, but only a smallish amount. Air leaks are the cause of almost all instances where the RPMs climb with the throttle still shut.

Find the leak and fix it. Then start figuring the rest of this stuff out. Do you have any hoses that go straight from the air cleaner to the manifold? You should not.

--DD

does sound like a vacuum leak of misplaced hose to me. Check your hose layout first, then look for cracked hoses...

The EFI numbers are correct for all the parts. I personally have not tested the MPS, but before it was purchased it was tested and passed without a problem.


I am in the process of checking my vaccum hoses for leaks, and for correct connections but I cannot seem to find a reliable schematic for the hose routing in the engine. All I have to work from is a shop repair manual, any suggestions where I might find another?

Thanks for all the suggestions guys!

-Todd

Compliments of Dave. http://www.pelicanparts.com/914/technical_...4_20FI_diag.htm

Excellent! Thank you, I will get right to work.

-Todd

OK guys- DRUMSTICKS & I are back on this project. We got the hose schematic from Pelican and new hoses are routed properly.
Then we gave the MPS a proper test with a gauge & pump instead of just the oral test and sure enough- doesn't hold vac. at all.
So I figure, problem solved and order a rebuilt MPS from Auto-ATL and hook it up - -- little change - still runs way too rich. ---DAMN!
NOW WHAT?
When I hooked up the MPS I just plugged in the elect. harness and slipped on the hose w/clamp- did not bolt it down. That thing doesn't have to be bolted down to work properly does it?

Where do we go from here?
The snow will be flying soon and it is still in the garage.
CHAZT

Did you check the adjustment on the FI Brain. I used to run mine 4-5 clicks from closed. CW to rich CCW to lean.

Adjusting the knob on the ECU will change things, but I don't think it's possible able to adjust it enough to make it idle at 4k RPM.

Start at the beginning.
Remove EVERY vacuum line from the plenum, put vacuum line covers on every port so you have no vacuum lines hooked up.

Now hook up JUST the mps.
Start the car...see if that cures it. If it does, its one of the lines.
Re-install ONE line at a time to find the system that is bad.

If that does not work (you can still get it to idle high)
you have to look at what you did...
That is specifically intake runners, throttle body, and all gaskets that go with that.
Check the bottom of the plenum for a rust hole...use a flashlight into the hole to see if there is a new hole that is not supposed to be there.

I have taken out the whole intake and I clean the head really well, then put a little smear of RTV Copper or Black on both sides of the spacer when I bolt it back to the head...that needs to sit overnight before you start the car.
Clamp the large intake runner rubber tubes on both ends...all of them.
Then, see if it still does it.

Throttle body gasket (is it complete, no missing pieces...use RTV if you have to to ensure you have no leak there.)

TPS setup...use the pic below to set it correctly at idle.
Idle circuit is special in Djet and you need to activate it by setting the TPS correctly...its a no adjustable thing...basically there is only one right way to set it...its not a variable...use the picture below.

Turn the knob on your ECU to zero...start there.
Go up one click at a time and wait ten minutes of running between any adjustment there.

Replace the CHT. check for shorts in the wiring going from the CHT to the ECU (pinout on Banders site)

Many times you will find the old wires break and short out...so its a good time to check the whole wiring harness...
Its time consuming, but simple to do with an ohm meter.

Rich

Like Dave said, idle that fast means there HAS to be a huge vacuum leak.

Thanks for the additional ideas guys, here is the status:

The throttle valve switch and intake mani gaskets are brand new. The FPS and the FI brain have not been touched since the car ran correctly, so we don't suspect them as being at fault. The TVS was removed and cleaned, and I will check the connections on the circuits when I can -- Which is more accurate for setting the throttle; matching to the picture, or setting with an ohm-meter?

Also, does it make a difference if the MPS is properly bolted in? We have been leaving it loose/unsecured in the bay as we test things.

Thanks again,

-Todd

no idea what an FPS is nor a TVS.
The MPS does not have to be bolted in.

You need to chase down the vacuum leak. The fact that you replaced gaskets it good, but you may have made a mistake when you put the intake system back together...
In order to rev at 4k rpms you need air.
If the throttle body is closed, you are getting air from someplace and it would be a large hole...

Check the intake like I said and redo it to ensure its super tight.
Check the injectors are in right...another vacuum leak.
Keep looking for a vacuum leak...you have one
There is no doubt, there is no question, there is no other explanation for a car that can run at 4k rpm with the throttle butterlfy closed...you need air to run that fast, and alot of it.

Rich

Thanks Rich

FPS - fuel pressure sensor
TVS - Throttle Valve Switch (throttle body)

I will check through everything as soon as I can, thanks for taking the time to walk me through it - I'm getting quite frustrated.

-Todd

The MPS has a mechanical component. If you shake it back and forth, you can sometimes hear the way the engine runs change. That said, it isn't completely necessary for it to be bolted down, particularly if you're not rolling down the road. Once you're done testing, bolt the MPS back onto its bracket again.

...You still have an air leak. A big one.

--DD

OK - we took your advice and dismantled the intake pipes and removed the throttle body assy and found the connector hoses to be pretty shoddy and the gasket at the base of the throttle body was in bad shape so we have ordered new hoses & gasket. We also found the inside of the conn. hoses to be saturated with gas/oil mix and also a puddle of gas/oil on the floor of the int. plenum.
Is this normal? or is this from the flooding out?

Somebody fill us in.

THANKS
CHAZT

There is no fuel pressure sensor...a fuel pressure regulator, yes.
The TPS is the throttle position switch.

The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else.
that is kicked off by the ambient air temp sensor (mounted under the plenum)
Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it...

I did that...it stopped running super rich.

Rich

yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there.

THANKS RICH.

You will need an inline gauge to confirm how the FPR is set.
I would suspect the cold start injector first...

Lets say its stuck open, and you keep getting fuel, no matter what.
If you unhook the elec, it will still be stuck open.
If you route the fuel hose around it and take it out of the loop, you wont be getting fuel anymore, but you may have created a new vacuum leak....so cap off both sides of the injector just to be safe.

I had to do this..it stopped the flooding.

IDK what your cold weather plans are, but I have driven it down to 20 degrees F with no cold start injector, no AAR, and no decel valve...it works fine without any of them till 20.
I noticed your address and you might be in the OMG it cold part of the country..but at least you can drive it till then.


rich

In a word, NO.
Follow the hoses back to the fuel pump and read the manual to get a detailed explaination of why that will not work. It will kill off your pump for one thing with no fluid in that part of the pump.

Rich

OK - so I need to replace the hose feeding the CSV with a longer one that will reach accross the engine and connect to the tee on the opposite fuel rail?
- and cap off the fuel line barb on the CSV and leave the elect. wires disconnected?

I just pulled the line off the CSV and plugged it... A pin that fit tightly and clamped.

That is exactly what I did.
Its about 2-3 feet of new hose and a few clamps...done.
Use the old hose and old clamps to close off the cold start injector just in case its stuck open.
I unplugged the elec first and that made no difference for me, so it may have been stuck open or leaking on mine...I never bothered to check.

Again, it really only comes into play when its really cold...otherwise its never used.
I suspect that is why it gets rusted and stuck...its used very rarely.

Rich

EUREKA!!
It finally runs & idles normal. That CSV must have been a main culprit all along because I never did find a major vac leak.

Thanks again for all your help. Now I 'd better change the oil and get rid of the diluted stuff.
CHAZT