jwbeck17

I am following your test directions as resistance is one thing to an injector, but voltage is the real measurement here, so I am following your test plan.

I have bridged pin 30 to pin 87 on relay XXV to provide 12V+ power to the IMR connector.

I am using an alligator clip from my Multimeter black cable to MP 1 for all tests, and have connected my red MM wire to an alligator clip clamping on a split spade connector with one of the ends cut off to create a tiny spade that can fit into the Bosch connectors on the injector harness

Test1:
I have bridged the center wire on the IMR connector to A1, or the red/green wire in the 89 schematic.

Hypothesis is that we should see 12V power on the red green wires of injector connectors for cylinders 2, 3, 5 and 8.

Cylinder 1: 1 mV
Cylinder 2: 12.35 V
Cylinder 3: 12.35 V
Cylinder 4: 168 mV
Cylinder 5: 12.34 V
Cylinder 6: -10 mV
Cylinder 7: -25 mV
Cylinder 8: 12.34V

Result: Cylinder connectors 2, 3, 5 and 8 are getting the correct voltage.


Test 2:
I have bridged the center wire on the IMR connector to A2, or the red/yellow wire in the 89 schematic.

Hypothesis is that we should see 12V power on the red green wires of injector connectors for cylinders 1, 4, 6 and 7.

Cylinder 1: 12.36 V
Cylinder 2: 100 mV
Cylinder 3: 60 mV
Cylinder 4: 12.36 V
Cylinder 5: 10 mV
Cylinder 6: 12.35 V
Cylinder 7: 12.35 V
Cylinder 8: -40 mV

Result: Cylinder connectors 1, 4, 6 and 7 are getting the correct voltage.

NOTE: The reason I am being detailed on the multimeter setup is that I originally tried to test this using the standard multimeter "nail tip" ends, touching the red to the power line and the black to the bolt on the crossbar. I was getting consistent results as above for the passenger side, but not on the drivers side. The drivers side was getting all -50-100 mV on cylinder connectors 5-8. I was using the passengers side cross bar bolt as the ground for the passengers side checks and the drivers side cross bar bolt for the drivers side checks. Since that ground change could impact the data, i switched to a single known ground for all checks, MP 1, which is where the readings are from here.

jwbeck17

This as a great suggestion, Theo. Just wish I had a spare injector to test with!

FYI - The injectors are only 3-5 years old, as Stan had changed them during an intake refresh.

jwbeck17

Now that I was able to confirm 12 V to the correct cylinder injector connectors, I tried the earlier test Greg mentioned.

I reconnected all of the injector connectors, kept the XXV jumper in place, and jumpered the center wire from the IMR connector to A1 and A2.

While the thermo elements are disconnected behind the engine as I haven't figured out a way of reconnecting them, they should not be a component of this test as they are affected by E1 and E2 in the IMR connector.

I was able to start the engine (it took a few seconds but started and idled on its own, and after a few minutes I was then was able to roll under the car and thermo gun the temps on each pipe of the exhaust manifold as it exits the engine block.

Cylinder 1: 154.4 F
Cylinder 2: 392.0 F
Cylinder 3: 441.1 F
Cylinder 4: 201.5 F
Cylinder 5: 214.7 F
Cylinder 6: 431.4 F
Cylinder 7: 472.1 F
Cylinder 8: 207.0 F

It looks like cylinders 2, 3, 6, and 7 are the hottest.

I then stethoscoped each injector head and heard equal clicking from each.

Next, I unplugged the injector connectors one at a time from 1, 4, 5, and 8. Each one resulted in a drop in RPM.

Does this mean that the harness is actually injecting fuel in all 8 cylinders?

Is there then possibly an issue with the spark timing? Fuel delivery?

jwbeck17

Also an update on overall performance:
The car was able to sit at idle without driver interaction for 10 min or so. No significant "rev hunting", where the RPMs drop and rise again in rhythm approx. every second or two.

When the throttle was engaged, then different things would occur. A gradual throttle increase would equal the correct increase of RPMs until about 1800 to 2000 RPMs. A more aggressive throttle increase would create some crackle and popping from both the MAF and exhaust areas and have some RPM hesitation, but would quickly level out to the desired RPM up to about 2000.

After 2000 RPM, the crackling would be significant and you would get hesitation, but would level out after a few seconds at steady throttle.

Being very aggressive with the throttle ("quickly flooring it") would create crackle, and reduction in RPM that it could not recover from.

Also if i was aggressive with the throttle and took my foot off the pedal to have the car go back to idle, it would stall.

TheoJ

Hallo Jason,
the temp reading of the cylinders looks correct and both ignition and injection seem to work fine.
Back to the original problem: "After 2000 RPM, the crackling would be significant and you would get hesitation, but would level out after a few seconds at steady throttle."
To me it sounds like you might have a MAF issue or a problem with the LH ecu.
Regards Theo

GregBBRD

Well, that seems all correct and normal, although I still can't make sense of your temperature readings, below.

MAF upside down?
Wires to temp sender and charcoal canister vent valve switched? (This usually results in temp sender "smoking".)
Plugged injectors?
Bad MAF?
Bad LH?

ammonman

If you really are getting fuel and spark at all 8 cylinders then the issue comes down to timing or the mechanical condition of the valves and pistons i.e. compression. Any chance you can swap the Kroon harness into a known running car to eliminate this as a possibility? You said in your first post that the MAF, EZK, and LH were all installed in a known good car and it ran flawless. Since that was likely some time ago can you repeat that test to verify? If yes, swap each one over one at a time and run in the test car before putting back into your car and swapping over the next item. If that all checks out I'd verify the base timing of the crank and cams. Have you run a compression test? Any chance the shop that did the A/C work messed with the timing belt tensioner adjustment bolt? Is the timing belt tension correct?

Mrmerlin

please do a compression test as Mike suggested

jwbeck17

Thank you all for your feedback as these are all good suggestions and next steps. My tests are showing that the cylinders are getting spark and fuel injection, though there are temp differences.

Let me answer some of your questions to help define next steps:

• Bad MAF?: I originally thought this too, and so I had the MAF sent out to be checked and rebuilt (it was slightly out of spec) about 2 months ago. I also tested it in a known good car with Stan approximately three weeks ago and it ran fine.
• MAF installed upside down?: While definitely possible, I have always installed it using the air direction arrow on the side going down into the intake, so I don't think that's the issue.
• Bad LH?: While this can create the same symptoms we are seeing, mine was rebuilt approx. 5 years ago along with the EZK. The LH and EZK were also tested in the known good car three weeks ago at Stans and performed correctly.
• Wires to Temp Sender and Tank Vent switched?: Stan and I thought there could be some incorrect connections, so I checked the connectors to the appropriate pins in a continuity test and confirmed the connections are correct. No smoking.
• Plugged injectors?: This I have not tested however the injectors were replaced by Stan 3-5 years ago. Still a possibility. Have to figure out how to test for that.
• Loss of compression?: This is also a possibility as I have not performed a compression test. Have to figure out how to test for that.

Now, I had a random thought in the middle of the night that I have no idea could be part of the issue, but it doesn't hurt to check.

Is it possible that installing the harness may have corrected one problem but created a new one that acts the same way?

While I was having poor starting prior to the harness installation, I didn't have the crackling and hesitation and stalling as bad as I do now. When I installed the ignition harness, I had to take apart the fuel lines behind the intake. Once the harness was installed, I reinstalled the fuel lines (they are approx. 3-5 yrs old Greg Brown ones, so they are in good shape). However did I install them correctly?

I went out this morning and took another look. The U line was a little more V-shaped then i think it should be due to how it was tucked. Granted, it's most likely not causing an impact, but the kink could be creating uneven pressure in the fuel system, which may impact the amount of fuel going into some injectors (a theory).

So this am I went in and removed the line, heated it up with a hair dryer to warm it up and reset the gradual curve, then reinstalled it to ensure the curve was smooth.

To give it the best chance, I am charging the battery now, so I have not tested it yet, but will this afternoon.

If that fails changing the performance, I suspect an injector check or compression test would be in order.

Will provide an update.

SwayBar

Amongst other things, a compression test will reveal if your cam timing is correct - both banks should be within 5 psi of one another. Not sure of S4 numbers, but thinking they should be 190-195 psi.

Another item to check is fuel pressure. You apparently have enough for low RPM, but maybe not for much higher.

jwbeck17

So I was able to test my kinked fuel line theory and I debunked it. It was not an issue with the fuel line, though now it is positioned better. The car has the same issues.

I plan on running a compression test and a fuel pressure test as soon as I can and will share what I find out. Will also check on testing the injectors themselves.

jwbeck17

Was able to run a compression test today. Since I was new at this, it took me a few tries to make sure I was doing it right to get consistent results. Here is what I got from a dry test:

Cylinder 1: 200 psi
Cylinder 2: 190 psi
Cylinder 3: 200 psi
Cylinder 4: 190 psi
Cylinder 5: 190 psi
Cylinder 6: 190 psi
Cylinder 7: 210 psi
Cylinder 8: 205 psi

While my compression kit may not be super accurate or my technique may not be perfect, those compression numbers look good to me, though I am not sure about the cylinder differences. That could be user error.

I know there was a question of timing earlier. The TB was replaced and in the spring, and I checked the cam positions at TDC about a month ago and they are dead-on.

Any more knowledgeable thoughts on this?

Next, I plan to do a fuel pressure test.

Mrmerlin

the compression numbers look good and they are pretty even.
So far nothing here explains the odd temp readings from all 4 of the outer cylinders.

NOTE odd running will occur when the battery is first reconnected,
It can take up to 25 miles for the injection system to normalize.

To speed things up do a few full throttle events up to about 4500 RPM in the lower gears so you dont get too fast.

Kevin in Atlanta

Clogged injectors. Have they ever been out for cleaning?

Landseer

Impressive data collection and thoughtfulness.

Here are some of the backyard mechanic things I've stumbled on when trying to clear up intermittent bad missing at some rpms:

Nicked coil or plug wires.(doesnt take much)
Cracks or carbon traces in distributor caps
Bad / wire broken O2 sensor
A couple swapped plug wires
Any of which could happen during TB job.
But you replaced that stuff, right, including coils...after the ac work?


Clogged or partially clogged injectors. For one of my cars that sat for many years this was a problem. But one measurable side effect was very lean, very hot running

Not very scientific. Just trying to help. I've had all of above cause problems on 32 V cars.

And one more...bad valley ground...where 6 or so grounds wire corroded in the lug. Very bad running, like having water in gas.