Running poorly/misfiring, code 33

[dave w]

I am running a HEI distributor using a 7 pin module.
I bought a aftermarket HEI distributor for the AMC/Jeep V8. It was for carbed engines and had a 4 pin module.
The pad the module sets on was the wrong shape and size to fit the 7 pin module. But strangely, the top half of the distributor could be removed from the shaft. I figure it was so the company could use the same top of different lower shafts for different engines.
I ended up buying a used distributor from a TPI chevy 350, chucking it up in my lathe and machined it to fit the aftermarket lower housing.
I ended up using the chevy shaft, rotor and top half of the distributor and only using the bottom lower housing of the aftermarket unit.
I am using the pickup coil and 7 pin module from the TPI distributor. I attached the two together using some small bolts. They are all still tight and rock solid. Nothing appears to have moved either.
It sounds kinda hodge podge, but it had been great and completely trouble free for years.

I will unbolt and check all my grounds. The battery posts are good and clean. I use AGM batteries, so no powdery corrosion.

The pickup coil and 7 pin module I swapped were used/junkyard units I kept for spares. They are factory GM parts.
If there is a chance they could be the issue, I do not mind buying new ones, if a QUALITY replacement can be purchased. I do not want some cheap china crap that will give me trouble in a couple months.

7 Pin HEI Large Cap with the Ignition Coil in the cap is a very good ignition system.

Possibly the 7 Pin Module is faulty?

Quality parts? No longer available, just cheap and worthless parts.

7 Pin HEI.png

[In-Tech]

Hiya,
Buy Delphi at Rock Auto. Fack AcDelco and all the other crap for sale. The originals were probably from the Philippines. Good luck with that.

[MO LS Noobie]

Can you elaborate on this a little? This is the first I have heard about this. However I have been out of the fuel injection/tuning loop for a few years. Plus I do not work on much anything other than my own stuff, so I do not have much exposure to common issues happening to similar vehicles.
I am a small engine mechanic for a living, so I do not get much exposure to working on cars/trucks.

Try this link, it explains it better than I can.
https://members.iatn.net/techmail/vi...ruck&kw=N41588

https://members.iatn.net/techmail/vi...ruck&kw=N41588

This is one of the posts if you have trouble opening it. "I have heard a lot lately about the pickup in the distributor being the cause. The pickup itself or the trigger wheel (for lack of a better term.) Check into that a little deeper if you have not. It can develop a crack or get loose on the distributor and cause these types of problems."

"also ran onto one that exhibited similar symptoms that ended up being a faulty coil that was leaking voltage out of the coil wire tower over to the primary wire connector. I saw a loss of signal from the module accompanied with a marked increase of system voltage due to HEI voltage leaking into the primary circuit."

[JeepsAndGuns]

Try this link, it explains it better than I can.
https://members.iatn.net/techmail/vi...ruck&kw=N41588

https://members.iatn.net/techmail/vi...ruck&kw=N41588

This is one of the posts if you have trouble opening it. "I have heard a lot lately about the pickup in the distributor being the cause. The pickup itself or the trigger wheel (for lack of a better term.) Check into that a little deeper if you have not. It can develop a crack or get loose on the distributor and cause these types of problems."

"also ran onto one that exhibited similar symptoms that ended up being a faulty coil that was leaking voltage out of the coil wire tower over to the primary wire connector. I saw a loss of signal from the module accompanied with a marked increase of system voltage due to HEI voltage leaking into the primary circuit."

It will not let me read it without logging in.

[JeepsAndGuns]

It is possible you are getting multiple injector pulses per cylinder because of a cracked pole piece in distributor.

I did not really think much of it when I saw it, as I thought it was either just me, or the spark tester.
But when I had the spark tester hooked up, and I was cranking it with the bypass unplugged to see if it was sparking, I swear it almost looked like it double sparked a couple times.
It is a inline spark tester that has a light bulb inside it that flashes. Normally you see the flash, but a couple times, it almost looked like two super fast flashes at one time.

So is it possible we might be onto something here?
You say possible multiple injector pulses, so if it is seeing a extra erroneous pulse, it will pulse the injectors again?


Now I am almost wanting to think I fixed one issue and created another.
I think the original missfiring might have been the pickup coil, that I swapped out for a used one I had, and the used one has a different issue.
Ever since I swapped them, I have not had the missfiring, but I can not set base timing and it's running rich. I am thinking the reason I can not set base timing is it is running too rich and floods.

I'm going to order up a new pickup coil and see what that does.
Looks like my choices that I can find are either wells or standard motor products. Either one of those brands any better than the other?

[MO LS Noobie]

I prefer Standard over Wells but all parts are a crap shoot lately, with so many counterfits from China.

PM me for log in info for the other site.

[JeepsAndGuns]

So looking up the pickup coils for TPI V8's, apparently there are two different ones.
There is a LX324, listed for a camaro, and a LX320 for the corvette. (both standard motor products part numbers)
They both look identical other than the color of the connector. The camaro is yellow while the corvette is black.
The part numbers for the distributors are also different, but they look the same.
Any idea what the difference could be?
The yellow camaro connector fits lots of chevy and gmc, while the black corvette connector fits lots of buick olds, and pontiac

I am pretty sure I am using the yellow connector pickup coil (camaro). I will have to pull the cap back off and double check.

[dave w]

So looking up the pickup coils for TPI V8's, apparently there are two different ones.
There is a LX324, listed for a camaro, and a LX320 for the corvette. (both standard motor products part numbers)
They both look identical other than the color of the connector. The camaro is yellow while the corvette is black.
The part numbers for the distributors are also different, but they look the same.
Any idea what the difference could be?
The yellow camaro connector fits lots of chevy and gmc, while the black corvette connector fits lots of buick olds, and pontiac

I am pretty sure I am using the yellow connector pickup coil (camaro). I will have to pull the cap back off and double check.

I'm thinking the large cap HEI with the coil in the distributor cap is for the Corvette. (7 pin module)

I'm thinking the externally mounted coil using the small cap HIE is for the Camaro. (8 pin module)

[MO LS Noobie]

HEI also had 2 different coils, different color wire to coil itself. Don't forget the coil grounding strap (top of coil under thin plastic cover).

[JeepsAndGuns]

Looking up the parts on rockauto, a 1985 camaro with the 305 tpi V8, and a 1985 corvette with a 350 tpi V8, they both show a large cap HEI distributor and they both look identical, but have different part numbers.

The pickup coils look identical but have different part numbers.
Camaro: https://www.rockauto.com/en/moreinfo...t=7176&jsn=595
Corvette: https://www.rockauto.com/en/moreinfo...t=7176&jsn=599

The coils (both large cap hei coils) look identical, but have different part numbers. The corvette has a red and yellow wire, while the camaro has a red and white.
Camaro: https://www.rockauto.com/en/moreinfo...t=7060&jsn=497
Corvette: https://www.rockauto.com/en/moreinfo...t=7060&jsn=558

The 7 pin module is the same part number.


Ok, doing a little more digging, I found reference to different ignition coils and that they need to be matched to the pickup coil. He says the coils function the same, but the polarity is reversed on the two, so the pickup and coil have to match.
https://www.chevelles.com/threads/he...rence.1089204/

I think I am just going to have to pick one (either camaro or corvette) and order both the pickup and the ignition coil, just so I know they are both matched, as right now it is a mix of junkyard parts.
The pickup I pulled out had the yellow connector and I am pretty sure the distributor came from a camaro. So I think I am going to pick that.
And yes, I do have the ground strap in place. I specifically remember putting it back in there.

[JeepsAndGuns]

Ok, so I ended up ordering the pickup coil and ignition coil for the camaro. I got the standard motor products pickup coil, and a ngk ignition coil.

The pickup and coil shipped separately, so I got the ignition coil first and swapped it out, but did not bother trying to start it. The pickup coil came a few days later and I managed to get it in yesterday. (I have a couple days off work).
Once I got the distributor reinstalled, I started it and it ran pretty crappy. I figured I did not have the distributor back in the exact same spot, even though I had marked it.
I ended up turning it a little while running and it smoothed out some. (had to retard it just a little). It was still running rich though.
Once it got up to operating temp, I shut it off, disconnected the bypass, crossed my fingers and tried it. Holy crap it started! I was finally able to set the base timing.
I reset the ecu and start it back up. It pretty much sounded normal. Seemed to throttle up and down ok. I drove it around my yard a couple laps with no issue, so I decided to go for a short trip 1/4 mile up the road to the intersection and back. It seemed to run normally, however it was still running rich. Generally around 12.5 on the wideband, but sometimes going as low as 11.5 and sometimes as high as 13.5. But it generally stated between 12.5-13.5
I think, maybe it just needs run and to "blow the soot out of it".
I drive it a couple miles away and back a couple times and got on it a few times. AFR never changed from the above.
It was lunch time by then, so I ate lunch at the house and hooked up tunerpro to it.
I start looking at the blm tables and everything is 128. I go for a short trip up the road and back, check the tables and everything is 128.
I was confused until my dumb-"you know what" looked at the main dash and saw the o2 sensor voltage was stuck at .450-something and was not moving or changing at all, and it showed it was in open loop.
No trouble codes were set though. I would have thought it would have set a code if it saw it was not reacting.

I checked the sensor and the plug and they looked fine. I am thinking maybe the o2 sensor has took a crap.
It is raining now so I can not check the wires and make sure power/ground are ok (it is a 3 wire sensor). But I think I am going to go ahead and order a new sensor.

The sensor is the 3 wire sensor listed for the 92-94 chevy C1500 5.7.
I have choices of NTK, delphi, denso, and a couple other off brands.
I have generally had good luck with ntk o2 sensors, and poor service life from bosch sensors. Any reason to pick a delphi or denso over the ntk?

[1project2many]

This is real progress! Nice!!

I use NTK, Delphi, or Denso sensors. I don't trust Delco branded products anymore and I seem to have consistently bad luck with Bosch.

Is there any chance the calibration is set for open loop only? It's free to check...

Also be sure to check for power / ground on the heater circuit. Cold sensors don't talk.

[JeepsAndGuns]

I have not changed anything in the tune, so unless it reprogrammed itself, it should still be set for closed loop. Plus it was working fine before the issues all started.
I'm thinking all the time I have spent trying to diagnose the issue and it running rich and dumping fuel into the exhaust, then setting for a few weeks between times running, has probably killed the sensor. I know raw fuel is not good for them.
I am going ahead and ordering a new sensor anyways, they are not very expensive, but will double check the power, ground, and sensor wire in the meantime.

I found a good price on the sensor on ebay for $14.99 with free shipping.
Looks like it fits several chevy and GM vehicles. I went ahead and ordered two, to have one as a spare.
https://www.ebay.com/itm/325453630014
Not sure if anyone else has a vehicle that uses that style, but figured if you did, here is a decent price on them.
NTK 21003 is the part number.

[1project2many]

I have not changed anything in the tune, so unless it reprogrammed itself, it should still be set for closed loop. Plus it was working fine before the issues all started.

It's happened to me! It's rare, but it's worth checking your prom to see if it matches your calibration.

Not sure if anyone else has a vehicle that uses that style, but figured if you did, here is a decent price on them.

That's a crazy low price. Hopefully it's the real deal.

[MO LS Noobie]

Has the new sensor arrived and have you installed it? Interested in how all of this plays out.