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914World.com _ 914World Garage _ d-jet issues

Posted by: bd1308 May 29 2006, 05:46 PM

So I get this new engine and put it in, runs great! Thanks Garold, you're a lifesaver.

I dirve it for a while, and notice that cold idle is REAL low. Warm it idles just a tad low, but at idle it runs RICH....

lowered performance until 1500(small amount of bog), then peaks at power at 3500

I drive at around 3500 usually (keeps it cool)

Idle it runs rich, so I adjust the knob on the ECU, and I dont want it to run lean at idle. So back to the notch it goes, where its rich.

I have 3 Mps's in all, including the Type III one which doesnt have a diapragm as noted in another buried thread....So in all, I have four MPS's. The one currently in the car is the "NOS" one that I paid too much for from a member here. Whatever. It didnt leak down a year ago, so I assume its still good, being that I just now used it.

In four days im getting into rust repair, upon which the engine will be dropped...mayeb then I could do a valve adjustment and take care of some things.

It's has some clicks at idle, maybe from the valves?

For the rich thing, maybe the trigger points went bad? I'll try some from the VW guy tomorrow, he has a box with a new one in it, or i could pull one from a rebuilt dizzy I have from cardone.

Any comments (less the "sell the 914" ones) add them below

Car runs though!

b

Posted by: bd1308 May 29 2006, 06:27 PM

oh and I cant the dwell angle to go any higher than 40 degrees either. 48-55 degrees is where the book says it should be.

Points suck.

b

Posted by: Bleyseng May 29 2006, 06:32 PM

Ok, fill us in on what engine you are now running......

Posted by: Mueller May 29 2006, 06:32 PM

there is no possible way for the trigger points to cause a rich condition...well maybe if they bounced like hell, but I couldn't see that happening unless you ran the motor to 20K rpms or higher

are the points new??

Posted by: bd1308 May 29 2006, 06:35 PM

they arent new new but they arent 5k miles old.

I'll change them when i get paid on thursday. Or just go pertronix.

b

Posted by: lapuwali May 29 2006, 06:48 PM

Pertronix doesn't replace the trigger points, just the ignition points. Trigger points usually last a very long time. Check the system voltage, and make sure the alternator is putting out a proper 13-14v.

Posted by: bd1308 May 29 2006, 06:56 PM

I know that...I was referring to the ignition points on my post.

I know that a low voltage will cause a rich running condition....

It just kinda bogs, thats all....

i'll check out teh mps, do valve adjustments and oil change, CHT guage and oil temp guage sender install...

b

Posted by: ptravnic May 29 2006, 07:06 PM

I'm not sure if you have or have not checked out Paul Anders's writeup on D-Jet.

Check it out here:

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

One step at a time. Wish I could help more.

-Pete

Posted by: Jeff Bowlsby May 29 2006, 07:14 PM

Idle during warm-up is controlled by the TS2. When operating temps are up to normal, or when the accelerator is moved, the switch inside the TPS or the warm engine condition signals the ECU to control pulse width.

Verify the resistance values hot and cold of the TS2 with the Anders page values. Your TS2 may simply be going out.

Posted by: bd1308 May 30 2006, 05:45 AM

Jeff, I switched out the "NOS" mps (I opened it--it aint NOS) with the one that came on the car, started it up and.....it started right up. no flooring the gas when cranking, no hesitation, nothing...Just pure 914 enjoyment. Engine sounds MUCH better too.

Jeff, are the calibrations different from a 1973 1.7L mps and the rest of them?

b

Posted by: ptravnic May 30 2006, 06:28 AM

Britt,

MPS's are not created equal. Part numbers need to be matched to the correct system. From Paul Anders's writeup and specs on the Bosch D-Jet:

Porsche/VW # Bosch # Engine Year
039 906 051 0 280 100 043 2.0L 1974 - 1976
022 906 051 C 0 280 100 037 2.0L 1973
022 906 051 E 0 280 100 049 1.7L 1970 - 1973

I honestly don't know what the "C' or "E" means on the Porsche/VW # but the Bosch #'s should also be stamped on the MPS. Your "NOS" might not be the right one for your setup or maybe the one which was originally on your car had been adjusted...

FWIW, I tested a mismatched MPS on my car this past weekend and it would barely start. I'm trying to find a local mechanic who can correctly tune my MPS - not an easy task b/c it requires shop quality equipment (CO meter, etc).

-pt

Posted by: krazykonrad May 30 2006, 06:34 AM

I would start by replacing hoses. Pull em out and put new ones in. It will suprise you where you have vacuum leaks that you didnt even know about. once you've fixed those, then worry about FI tuning. If not you'll be tuning for the vacuum leak(s) and not to where its really supposed to be.
Cheers and best of luck!
Konrad

Posted by: bd1308 May 30 2006, 06:35 AM

All it requires is a inductance meter--some 175+ dollar meter that I long for.

I am getting a D-jet tester (VW 1218 like I always wanted) very soon.

b

Posted by: ptravnic May 30 2006, 07:35 AM

To check for vacuum leaks, get a small jug of propane and spray the propane arnound every hose/clamp/elbow/connection while your car is idling. If the idle reacts when you point the propane at a certain hose/clamp/elbow/connection then you know where the leak is coming from. No need to just replace the hoses, most are prob fine - might just need a tighter clamp on an end or something...

-pt

Posted by: bd1308 May 30 2006, 01:30 PM

0 280 100 003 (VW) 022 906 051

I think I have a 1973 1.7L Fi system, as my engine had the paper filter on it (paper type) but not flat, its round.

b

Posted by: Rand May 30 2006, 03:00 PM

Low idle, I wouldn't suspect a vacuum leak or bad hose (unless maybe the MPS hose is bad and the MPS isn't getting the vacuum to pull it off of full-rich). Normally Djet vacuum leaks cause lean/high idle, right?

Hey Britt, I'm sure you've already covered this, but just in case...

Be sure and mark the adjustments so you can return them back to a starting point if needed. Have you opened up the idle/air screw on the throttle body? Is the AAR working?

Posted by: bd1308 May 30 2006, 06:42 PM

I took the AAR out actually.

I wasnt as concerned about the Idle RPM as much as the MIX concerned me.

I realized the consequences of subtracting the AAR.

b

Posted by: Rand May 30 2006, 10:17 PM

You mentioned cold idle is low. No AAR accounts for that. I guess I'm stating the obvious.

How are you measuring the mixture?

Posted by: bd1308 May 31 2006, 02:07 AM

I could smell burned gas from the inside of the car, and black smoke...

b

Posted by: Bleyseng May 31 2006, 03:27 AM

Too rich a A/F mix usually is:
1. misadjusted MPS
2. Dead CHT
3. Stuck injector(s)

It does take much turning of the inner screw to change the A/F mix on a MPS. You can send it to me in Seattle and I'll re set it to stock. I'll be back in about 10 days.

Posted by: bd1308 May 31 2006, 03:36 AM

Geoff, is a inductance meter all that is fundamentally required to tune these things, and referencing brad anders' website with the calibration chart?

After getting a VW 1218 tester AND several working mps's I think i'll be sticking with D-jet for just a while longer. The day I switch is when my last mps dies. As of now, I have no REAL reason to go megasquirt...I'm not running a massive cam (would like the 9550 Raby Djet cam tho) nor am I running some huge displacement size.

I'm just gonna freak when my mps's all die. I wish I could buy those new diaphragms, but 500+ bucks for a rebuilt mps with new diaphragms is just too much I would think. Although, if it lasts for 30 years, its a good deal.

b

Posted by: Bleyseng May 31 2006, 03:52 AM

The tools needed to open up a MPS are:
1. a drill and assorted bits
2. Heat gun to heat up the epoxy coating
3. large screwdriver
4. 16mm fine thread tap
5. assorted sealants
6. Wavetek meter
7. vacuum pump

0r

8. LM-1 meter to set the MPS to your motor using a wideband O2 sensor.

If one is running way rich check to make sure its not leaking!

Posted by: bd1308 May 31 2006, 03:57 AM

I opened the problem mps up and everything looked great so I suppose my problem was in the adjustment and not in the "blown diaphragm" like I had thought.

b

Posted by: Bleyseng May 31 2006, 07:12 AM

Did you reseal it so it hold a 15hg vacuum for atleast 5 minutes? If not, that is your problem not the adjustment.

You can also go to a dyno shop and dyno the car and adjust the MPS after each "pull" to set the MPS properly. Under load is the best way to set the A/F.

Posted by: bd1308 May 31 2006, 07:17 AM

The one I opened is still sitting on my desk.

Since its working now, i'm just goign to leave it. I have to take the engine out tomorrow morning anyway for my Rust-A-Thon at noon.

b