Troubleshooting help 1.7 FI, Updated: I almost have defeated the D Jet Demons! Options

[rjames]

Since the engine was rebuilt, it's definitely possible that the MPS now needs to be calibrated to accommodate the new build. (Has the MPS been opened by someone else?)

Having it calibrated to stock #s by someone on the bench may or may not not get you where you need to be. You need to get it in the ballpark so your car will idle, and then tune it via wide band O2 sensor. You could easily do this yourself with the adjusting tools from Tangerine.

[emerygt350]

Check your wires, check your timing. It very well may turn out to be the weird mps issue mentioned above but you have a whole lot of little stuff you can do before you go running straight to the ... MPS.

[Robarabian]

UPDATE: Still struggling.

I have a properly working MPS, a properly calibrated and working throttle position sensor. I put hose clamps on all the intake boots to eliminate any leaks there, sprayed soapy water while holding the throttle open enough to keep it running and didn't locate any leaks.

The 123 dizzy vacuum line is disconnected, and the lines to the throttle body are plugged. IT cranks and fires with a revolution or two (ie., a second or less of cranking) runs for 2 seconds and still dies.


The throttle is still sluggish and I cant really properly time it still. I have moved the dizzy a bit... retard it coughs through the intake, too much advance it dies immediately, so it is set right in the middle right now where it starts very easily.

Valves were adjusted. Fuel pressure at 29 psi and does not drop while under load. Injectors were replaced as well during the rebuild (Fj 114) with new o rings / seals; No fuel leaking anywhere;

Really the only things hooked up are fuel lines, MPS, cold start valve, thermo time switch, Cyl head temp sensor (made sure plugged in and also verified car won't start without it) and the AAR. I followed Ian KArr's procedure from his video, it Ohms out at 12.9 and the heat element works as well as the cylinder rotates freely inside.


Any more thoughts?

[914_teener]

UPDATE: Still struggling.

I have a properly working MPS, a properly calibrated and working throttle position sensor. I put hose clamps on all the intake boots to eliminate any leaks there, sprayed soapy water while holding the throttle open enough to keep it running and didn't locate any leaks.

The 123 dizzy vacuum line is disconnected, and the lines to the throttle body are plugged. IT cranks and fires with a revolution or two (ie., a second or less of cranking) runs for 2 seconds and still dies.


The throttle is still sluggish and I cant really properly time it still. I have moved the dizzy a bit... retard it coughs through the intake, too much advance it dies immediately, so it is set right in the middle right now where it starts very easily.

Valves were adjusted.

Any more thoughts?

Yes:

Get the timing set statically first per specs if you checked the valves since all the holes are plugged.


Then make sure your fuel lines and or hoses aren't kinked. Make sure the fuel pressure is spec once you have eliminated a fuel problem.

Make sure you are using the right coil per the 123 instructions.

All electrical leads including the connector at the ECU...mine was loose once. Also the lead to the CHT...make sure it's not cracked or loose, along with ALL the FI connectors at the center spade underneath the plenum. Anything else you might have touched when you took the motor out...electrical connections ect.

After all that then it's time to look at spark and the dizzy.

[Robarabian]

Ok, I haven't checked the plug at the ECU... I'll do that tomorrow.
I'll swap out the coil for the one I purchased from 123 as well. Will report back!

UPDATE: Still struggling.

I have a properly working MPS, a properly calibrated and working throttle position sensor. I put hose clamps on all the intake boots to eliminate any leaks there, sprayed soapy water while holding the throttle open enough to keep it running and didn't locate any leaks.

The 123 dizzy vacuum line is disconnected, and the lines to the throttle body are plugged. IT cranks and fires with a revolution or two (ie., a second or less of cranking) runs for 2 seconds and still dies.


The throttle is still sluggish and I cant really properly time it still. I have moved the dizzy a bit... retard it coughs through the intake, too much advance it dies immediately, so it is set right in the middle right now where it starts very easily.

Valves were adjusted.

Any more thoughts?

Yes:

Get the timing set statically first per specs if you checked the valves since all the holes are plugged.


Then make sure your fuel lines and or hoses aren't kinked. Make sure the fuel pressure is spec once you have eliminated a fuel problem.

Make sure you are using the right coil per the 123 instructions.

All electrical leads including the connector at the ECU...mine was loose once. Also the lead to the CHT...make sure it's not cracked or loose, along with ALL the FI connectors at the center spade underneath the plenum. Anything else you might have touched when you took the motor out...electrical connections ect.

After all that then it's time to look at spark and the dizzy.

[emerygt350]

My 2.0 will run 10 degrees retard and 50 degrees advanced. This issue seems to be something very fundamental.

Have you verified the plug wires are absolutely going to the right places. Have you checked tdc on cylinder 1 and the location of the rotor and corresponding plug tower? Installing the 123 can lead to some weird things. I took 3 stabs at it and a call to tangerine racing before I actually got it right.

Since your car ran before I would focus on a confident 124 install first. Again, a vacuum leak on a d-jet just means a high idle. Sure your mps could have died all of a sudden or be suffering from the weird pertonix thing, but a miscalibrated 123 install is the simple explanation.

[Robarabian]

UPDATE 7/21/24

I pulled the brain and checked everything. Very clean inside, all the contacts were clean and dry. I have a spare brain from a 73 that has the little knob on it. Plugged it in, it started right up, but died as the original computer does. Re-assembled the original one and put it back. It works AFAIK.

Switched the coil for the one I purchased from 1,2,3 ignition. Same issue.

Pulled the dizzy, put the car to TDC and re-installed. I made sure all the wires were in the right firing order (which they were) and noted that I was on TDC. There was a chance I did static timing before at the 27 degree mark, so I made sure I was on TDC. Reinstalled the 123, got the little green light and fired it.

It came to a stable idle, and after letting it warm up, I timed it to 27 degrees at 3500, no vacuum lines on dizzy. Using the tach function on the timing gun for RPM's.

Now, it still hunts a bit and the throttle response is slow, and I get a backfire out the tailpipe when I try to throttle it. The air bleed screw does have an effect, so although it was still idling high, screwing the idle screw down lowered it and I can choke it down to 950, but that is almost fully closed.

I am still thinking there is a timing issue... I am going to go dig out the original distributor that ran with pertronix and see if it remedies anything. But it's 97 degrees and Im too overheated to dig through boxes.

My 2.0 will run 10 degrees retard and 50 degrees advanced. This issue seems to be something very fundamental.

Have you verified the plug wires are absolutely going to the right places. Have you checked tdc on cylinder 1 and the location of the rotor and corresponding plug tower? Installing the 123 can lead to some weird things. I took 3 stabs at it and a call to tangerine racing before I actually got it right.

Since your car ran before I would focus on a confident 124 install first. Again, a vacuum leak on a d-jet just means a high idle. Sure your mps could have died all of a sudden or be suffering from the weird pertonix thing, but a miscalibrated 123 install is the simple explanation.

[914_teener]

My two bits:

1. Set static timing...."the green light". Once that is done you have set it.

2. I'd use the ECU with the idle mixture knob. Not sure why you aren't.

3. Make sure your AAR is functioning. You can bench test it. Make sure it fully closes.

4. Hook up your ported vacuum hose from the TB to the dizzy and all other vac hoses.

5. Adjust idle mixture and speed accordingly. Nice to have a wide band here but not necessary. You should have a steady idle...no surging at about 600 to 800 RPM.

6. Set timing.

[Robarabian]

Ok, I finally followed your advice:

Capped off all the vacuum hoses except the MPS. (upper and lower throttle body ports too)
Unplugged cold start valve, and air temp sensor. Left the throttle position sensor plugged in for some reason but keep reading.

Cranked it, it started and came to a high idle, and adjusting the air screw, it came down. I could have cranked it till it stalled frankly, but left it around 1000 rpms. I timed it at 3500 rpms and it maintained idle. Throttle response was slow but it works.

I plugged in the air temp sensor first and it immediately started lobing up and down wanting to die. I unplugged it and it stabilized. So there is an issue there. I had a spare one from a different year car and swapped them, but same issue.

So what is the way to test that specific sensor? On car, or off car? While it was running, I plugged in the cold start valve and got no changes, so that seems eliminated. Un plugged the vacuum block on the AAR and as it warmed up, the idle came down a bit more, as expected.

Throttle response still sluggish but it works. Your method works, it helps the process of elimination...

My two bits:

1. Set static timing...."the green light". Once that is done you have set it.

2. I'd use the ECU with the idle mixture knob. Not sure why you aren't.

3. Make sure your AAR is functioning. You can bench test it. Make sure it fully closes.

4. Hook up your ported vacuum hose from the TB to the dizzy and all other vac hoses.

5. Adjust idle mixture and speed accordingly. Nice to have a wide band here but not necessary. You should have a steady idle...no surging at about 600 to 800 RPM.

6. Set timing.

[914_teener]

Ok but the air bleed screw should be your last adjustment.


Here is a copy and paste from Brad Anders site for the Air Temp Sensor and the test procedure:

Function: Senses intake air temperature and sends signal to the ECU to provide mixture compensation.
Normal Value(s): 300 ohms @ 68 deg. F, about 100 ohms @ 122 deg. F.
Failure Modes
Open: Makes the mixture somewhat richer. Check with an ohmmeter.
Shorted: Makes the mixture somewhat leaner. Check with an ohmmeter.
Notes: The output of this sensor is used by the ECU to adjust the mixture for the intake air temperature. This is a secondary adjustment and has a small effect on the mixture. The sensor corrects for the decrease in air density with increasing temperature by leaning out the mixture. Disconnecting this sensor has the effect of richening the mixture, a common mechanic's trick.
More: This sensor and the cylinder head temperature sensor are negative-temperature-coefficient (NTC) thermistors. Here's a URL on thermistors and how they work:
http://www.rtie.com/ntc/ntcappln.htm

Here's a URL that describes the manufacturing process:

http://www.ussensor.com/manufacturing.html

Below is a URL to a reference that has two charts showing the resistance vs. temperature relationship for the intake air sensor and the engine temperature sensors used in D-Jetronic. The engine sensor data looks OK (about 2.5K at 68 deg. F), but could be from any sensor. Bosch used the same air temperature sensor on all D-Jetronic cars, regardless of model, so the data should be accurate for the 914's sensor:

http://www.icbm.org/erkson/ttt/engine/fuel...tion/d-jet.html

The charts are about half way down the page.



Read the page on idle stability. I'd use an ECU with the adjustment knob. It's also possible that you have a ground problem...which you can test for resistance. Make sure your ground strap is new or you could be chasing your tail...like you are. But it looks like it's not the timing.

My quess in you still may have a vaccum leak, leaky or bad PVC valve.

I'd test every single component but since the engine was out....a bad ground somewhere.

Memorize or reference Brad Anders site. All the answers are there.

[emerygt350]

Sluggish throttle response I am still going to have to go with some kind of ignition related issue. Plugs should tell you if it's too lean or rich at idle. How does the exhaust smell?

[Robarabian]

Exhaust is smelling rich....no visible smoke colors but smelly. The plugs dont have that old carburetor brownish color so it is definitely not lean. Theyre not all fuel fouled black either. Somewhere in the middle is what I would describe as.

As I continue to troubleshoot I will try and pull the 123 and throw in the Bosch with pertronix and see if there is a difference.

Thank you to all who are helping me with this I am not a D Jet expert and this has been a learning process.

Sluggish throttle response I am still going to have to go with some kind of ignition related issue. Plugs should tell you if it's too lean or rich at idle. How does the exhaust smell?

[emerygt350]

I would put some more advance into it, but since you are dealing with Bluetooth perhaps check the curve you are using? No idea how you do that though.

[914_teener]

I would put some more advance into it, but since you are dealing with Bluetooth perhaps check the curve you are using? No idea how you do that though.

(IMG:style_emoticons/default/WTF.gif)


Give me a PM....I'll be in CA after August 5th.

You can try the Pertronix but from what I understand or read it looks like electrical for the FI or the mixture. They are interrelated. A good DMM is your biggest friend here.

Test the sensor from my last post. To troubleshoot D-jet you really need a DMM.

[emerygt350]

The only thing that's part of d-jet that would do that is the mps and a dmm isnt going to do Jack for tuning an mps. If his plugs looked different I might think mix

However, incorrect timing is going to do that.

[914_teener]

The only thing that's part of d-jet that would do that is the mps and a dmm isnt going to do Jack for tuning an mps. If his plugs looked different I might think mix

However, incorrect timing is going to do that.

Meh....ignore.

[emerygt350]

What is your problem? Do you think I don't know how to troubleshoot a d-jet? Tell me how a temp sensor is going to cause his symptoms? The car ran on a pertonix.

[914_teener]

What is your problem? Do you think I don't know how to troubleshoot a d-jet? Tell me how a temp sensor is going to cause his symptoms? The car ran on a pertonix.

Don't have a problem. I won't answer the second question because I don't know you.

To answer your third question, I've already copied and pasted Brad Anders failure mode test for the Air Temperature test which involves using a DMM to check the OHMS across the too poles of the sensor.

If both the Air temp sender and the CHT are out of spec the mixture settings IF he is using the right ECU will be way off.

Also...and as I already posted...one of the ground or the trans strap could be old or loose. One of the first things anyone using D-jet should replace is the ground strap.

Again...you can test the resistance across the ends to see....using a DMM.

Also....and I don't know cause I haven't seen the car......yet...and I had this happen, if the harness is old one of the wires near the injector leads could be cracked and when then engine was removed could have cracked the leads on the FI harness....again....ringing out the leads helps but if there is only a partial crack it could have been fine before. The check is with....wait for it....a DMM and not a timing light.

I don't have a need to be right.

[emerygt350]

Then don't tell someone to dismiss another's suggestion, or find a respectful way to explain your reasoning that would lead to that outcome.

D-jet will run better than he is describing with half the sensors out of whack. I have experimented with altering the cht resistance and you can get away with a huge variance from spec and the car will run. Rich as a pig or lean as hell but it will run. Particularly when cold. Even with the mps vacuum unplugged. That is why I am thinking it's something else, like we are still only on a couple of cylinders or the dizzy isn't giving it any kind of advance.

If the mps vacuum is unplugged you can 'drive it' but it also won't have throttle response, but I can't imagine the mps vacuum hose isnt connected or something happened to the mps.

All of the other sensors just add a Little seasoning to d-jet. As is clear from brads site or if you disconnect them and operate the car.

Maybe it is time to pop the pertonix back on to verify nothing is broken. I believe he said there was some backfiring...

[Robarabian]

See top thread update...