85 Digijet rich sloppy idle. I've tried everything.

[joop]

I'd be curious what the ECU "sees" for the temp sensor used for warmup

This was my first thought also pile
When the sensor is disconected or bad or wires are bad your ecu sees a very cold engine.

Ok, if you think your problem is electrical related do some basic measurements at first. One of the most important things and often forgotten is to see if ALL the ground wires are really zero! Test it, not only unloaded but loaded also (between minus batt and at ecu connector. If you lose 1.5 Volt the inputs from the sensors are off by 30%
Check ALL the ground wires careful (also gearbox - chassis - batterie)
Do this very seriously, only then you can exclude things and go from that point.
Take care: bad grounds can destroy an ecu (when you start the engine)
I've seen many cars with high bills from reputated workshops with small electrical problems, when they start guessing and (even worse) starting to swap parts you don't end up with an happy customer

Joop

[mattcfish]

I'd be curious what the ECU "sees" for the temp sensor used for warmup

This was my first thought also pile
When the sensor is disconected or bad or wires are bad your ecu sees a very cold engine.

Ok, if you think your problem is electrical related do some basic measurements at first. One of the most important things and often forgotten is to see if ALL the ground wires are really zero! Test it, not only unloaded but loaded also (between minus batt and at ecu connector. If you lose 1.5 Volt the inputs from the sensors are off by 30%
Check ALL the ground wires careful (also gearbox - chassis - batterie)
Do this very seriously, only then you can exclude things and go from that point.
Take care: bad grounds can destroy an ecu (when you start the engine)
I've seen many cars with high bills from reputated workshops with small electrical problems, when they start guessing and (even worse) starting to swap parts you don't end up with an happy customer

Joop

I've checked all grounds and run an extra solid copper cable from the battery to the trans, to the block, to the firewall, and to the alternator bracket.
No change. I completely rewired the temp 2 sensor (including the plug to the sensor and the terminals to the ECU) no change.
I'm just wondering if 2.2L motors are too much for the Digijet FI. Has anyone had one that idled normally with this configuration? GW says it should, but I haven't talked to anyone who can verify that.

[Piledriver]

At this point you might be ahead installing a different adjustable FPR, the modified DJet ones with the manifold reference should work fine.

Between that and a WBO2 with an adjustable NB output you should be able to set the AFR anywhere desired.

[mattcfish]

At this point you might be ahead installing a different adjustable FPR, the modified DJet ones with the manifold reference should work fine.

Between that and a WBO2 with an adjustable NB output you should be able to set the AFR anywhere desired.

I've considered these modifications. Does someone sell modified Djet FPR's? Link? How about these cheapy eBay units? http://motors.shop.ebay.com/i.html?_nkw ... m270.l1313. Can't tell if they use manifold vacuum.

On the O2 sensor...are you talking about this http://www.magnumtuning.com/en/product_ ... adjustable ?

Sense the Digijet dizzy operates independently...I've also considered replacing the dizzy with something like this http://www.cbperformance.com/catalog.asp?ProductID=1855.
Thoughts?

Thanks for the input.

[Piledriver]

No, I'm talking about the std and modified genuine Bosch DJet units that several companies still sell as general purpose adjustable regulators.
Probably the finest quality product MSD sells...
http://www.jegs.com/i/MSD-Ignition/121/ ... tId=761218

You will have to add a "T" to your setup most likely.
May be time for new hoses anyway...

Most any WBO2 setup has a fake narrowband output option.

That "magnum" is just appears to be an intentionally miscalibrated narrowband and is IMHO snake oil.
(off to look for links)

Here... some assembly required, opt for longer wires.
Real wideband O2 setup with sensor for $125... but I don't think you can freely program the narrowband setpoint:
http://14point7.com/SLC-OEM.php

Any of the more expensive units have user programmable NB setpoints.

What voltage is your NB sensor putting out NOW?
(after exhaust fully heats up)

One more silly question:
How does it run?
If it's a dog, is your cat converter plugged?
(if you have been running rich long it may be trash)

[mattcfish]

One more silly question:
How does it run?
If it's a dog, is your cat converter plugged?
(if you have been running rich long it may be trash)[/quote]

No cat. The cat that came with the van was a hollow shell. I removed it. The O2 sensor on the Digijet screws in at the collector.
Ansa muffler for 1.9L vanagon. Somewhat louder than most Vanagons I've heard.
Uneven, rich smelling idle. Good excelleration, and smooth at high RPM's. Poor miledge. I got as low as 12mpg on a trip once. I advanced the timing a little and bumped it up to 18.

[Piledriver]

One more silly question:
How does it run?
If it's a dog, is your cat converter plugged?
(if you have been running rich long it may be trash)

No cat. The cat that came with the van was a hollow shell. I removed it. The O2 sensor on the Digijet screws in at the collector.
Ansa muffler for 1.9L vanagon. Somewhat louder than most Vanagons I've heard.
Uneven, rich smelling idle. Good excelleration, and smooth at high RPM's. Poor miledge. I got as low as 12mpg on a trip once. I advanced the timing a little and bumped it up to 18.

O2 sensor voltage when fully warmed up.
An adjustable FPR is probably where this is headed...
(A MS1 would be much better, but ....)

[mattcfish]

O2 sensor voltage when fully warmed up.
An adjustable FPR is probably where this is headed...
(A MS1 would be much better, but ....)

I've checked O2 voltage in the past. Can't remember the figure. Seems like it was within specs though.
Will check again.

[Piledriver]

O2 sensor voltage when fully warmed up.
An adjustable FPR is probably where this is headed...
(A MS1 would be much better, but ....)

I've checked O2 voltage in the past. Can't remember the figure. Seems like it was within specs though.
Will check again.

well, if it's reading ~..45v when you are running dead rich, it's borken.

An O2 sensor circuit/ECU will cause the mix to go rich/lean in a cycle has it hunts around lambda=1.0 when in closed loop, which should be most of the time once warmed up.
The sensor has a very accurate sharp transition there, but is quite useless for ~anything else.
At WOT you may have a swicth that kicks the FI into open loop at a richer mix.
The temp sensor we have discussed previously effects the mix and if you are or are not in closed loop as well.

If the switch is broken, temp sensor or O2 sensor is bad, and you are staying in open loop WOT enrichment mode...
... or If the O2 sensor reads "normal" voltage when dead rich, there's your problem.

Digijet/digifant are too primitive to throw error codes etc, it tells you sumtings wong simply by the engine running like guano.

Here's a link that has a reasonably straightforward explanation of a NBO2 sensors function, might also demonstrate a worthy small upgrade for the std single wire NB sensor you have.
http://mymiata.paladinmicro.com/Miata4-WireO2.htm
Also has a valid how-to for testing a NB sensor.

If your sensor is not bad, we can start looking at if you have a hard miss, low compression etc.
99% of "fuel injection" problems are really ignition problems in my experience, and that would explain the difficulty in "fixing" the EFI....

Also: What brand pistons did you use, and what was your final deck height?

[mattcfish]

O2 sensor voltage when fully warmed up.
An adjustable FPR is probably where this is headed...
(A MS1 would be much better, but ....)

I've checked O2 voltage in the past. Can't remember the figure. Seems like it was within specs though.
Will check again.

well, if it's reading ~..45v when you are running dead rich, it's borken.

An O2 sensor circuit/ECU will cause the mix to go rich/lean in a cycle has it hunts around lambda=1.0 when in closed loop, which should be most of the time once warmed up.
The sensor has a very accurate sharp transition there, but is quite useless for ~anything else.
At WOT you may have a swicth that kicks the FI into open loop at a richer mix.
The temp sensor we have discussed previously effects the mix and if you are or are not in closed loop as well.

If the switch is broken, temp sensor or O2 sensor is bad, and you are staying in open loop WOT enrichment mode...
... or If the O2 sensor reads "normal" voltage when dead rich, there's your problem.

Digijet/digifant are too primitive to throw error codes etc, it tells you sumtings wong simply by the engine running like guano.

Here's a link that has a reasonably straightforward explanation of a NBO2 sensors function, might also demonstrate a worthy small upgrade for the std single wire NB sensor you have.
http://mymiata.paladinmicro.com/Miata4-WireO2.htm
Also has a valid how-to for testing a NB sensor.

If your sensor is not bad, we can start looking at if you have a hard miss, low compression etc.
99% of "fuel injection" problems are really ignition problems in my experience, and that would explain the difficulty in "fixing" the EFI....

Also: What brand pistons did you use, and what was your final deck height?

Does the Bosch 13275 O2 have the same threads as the 1 wire used on VW's? Sounds like a great cold start upgrade.
I'm using GoWesty (Wiseco) 2.2L pistons. 0 deck height at the top of the barrel. Should be over 8:1 compression (was 9:1 but GW lowered it for some reason before I bought mine).
I've changed the O2 sensor several times without improvement, and checked the continuity of the wire. I even removed some of the coax shielding near the connector to make sure it wasn't shorting out. Can't remember what Voltage was, should be reading around 1V if it's running too rich, right.
I've run all of the ignition checks, and swapped in and out all of the components. I think I've covered that ground, but obviously I can't be sure I haven't missed something.
Thanks

[Piledriver]

AFAIK all O2 sensors share the same thread setup.

8:1? ... At least you only have the stock cam, it should still run ~OK with the std ~1mm deck from the head gaskets.

Unless the cam is installed way retarded it doesn't make much sense.

[mattcfish]

When at operating temp the O2 voltage fluxuates rapidly between .46 and .60V. I don't think the sensor is bad, I've changed it 3 times and the idle has been unaffected.
The plugs do not show signs of rich running, but the exhaust has a strong rich odor although there is no visible smoke.
The idle is rough at 7 degrees BTDC and runs very poorly, if at all, at the specified 5ATDC.
I've had a pro VW mechanic friend (who won't touch vanagons) tell me it's running rich.

[Piledriver]

Went back and reread from beginning...

Whatever happened to the weird in the harness?
(the bit you could squeeze and the manifold vacuum shot up to normal?)
That needs identified and fixed before doing anything.
Could be the temp sensor signal or such.

[mattcfish]

Went back and reread from beginning...

Whatever happened to the weird in the harness?
(the bit you could squeeze and the manifold vacuum shot up to normal?)
That needs identified and fixed before doing anything.
Could be the temp sensor signal or such.

Is the rapidly changing voltage normal from the O2?
I played around with harness for awhile. Rewired the temp II to no avail. All continuity checks show all wires are good. I can't seem to be able to replicate my wire grabbing and squeezing results.

For curiosity sake, there is a wire that goes from the O2 sensor plug #5 at the ECU to another terminal #6 and back out to the AFM (page 97.61 in the Bentley Manual). I gather this sends the .46 to .6V current from the O2 to the AFM #4 plug. What does the AFM do with that signal?
I should be able to pick that voltage up at the the AFM plug when the engine is running...and it should match the O2 signal. I'm confused as to why 1/2 of the wire from the O2 to the ECU is shielded coax, but the wire that brings the signal back out to the AFM is not shielded....? What effect does the partial shielding have?
Just want to make sure the O2 signal is getting where it needs to go.

[mattcfish]

Went back and reread from beginning...

Whatever happened to the weird in the harness?
(the bit you could squeeze and the manifold vacuum shot up to normal?)
That needs identified and fixed before doing anything.
Could be the temp sensor signal or such.

Is the rapidly changing voltage normal from the O2?
I played around with harness for awhile. Rewired the temp II to no avail. All continuity checks show all wires are good. I can't seem to be able to replicate my wire grabbing and squeezing results.

For curiosity sake, there is a wire that goes from the O2 sensor plug #5 at the ECU to another terminal #6 and back out to the AFM (page 97.61 in the Bentley Manual). I gather this sends the .46 to .6V current from the O2 to the AFM #4 plug. What does the AFM do with that signal?
I should be able to pick that voltage up at the the AFM plug when the engine is running...and it should match the O2 signal. I'm confused as to why 1/2 of the wire from the O2 to the ECU is shielded coax, but the wire that brings the signal back out to the AFM is not shielded....? What effect does the partial shielding have?
Just want to make sure the O2 signal is getting where it needs to go.

On second thought maybe the wire that goes to plug #4 on the AFM from plug #6 on the ECU is a ground wire that is not connected to the O2 signal wire, but instead to the shielding around it.