Electrical Howell EFI - No RPM Signal

[John Casey]

For those who had RPM signal problems at the ECU, were they caused by a grounding issue?

My situation is as follows:

AMC 258 i6 / 4.2l with Davis DUI
Engine cranked, but didn't start.
Tested spark, but no fuel after prime when cranking.
WinALDL revealed no rpm signal.
Talked to Troy at Howell, did the 3 x tac tests, and got the pump to run and injectors to click indicating a ingition or filter problem
Replaced the DUI module with OEM GM unit, no change
Replaced the tact filter and ECU with new ones from Howell, no change.
Read about voltage issue when the difference from neg batt post to engine is > .2v when cranking.
I was showing .39

I got it down to .3 by:
12ga wire from Howell harness grd bolt on the intake, to firewall on a mast cylinder bracket bolt.
Batt neg to same firewall bolt.
Instrument grd bus to other side of firewall to that same bolt.
2 X OEM grd on headlight harness to a different firewall bolt
Other side of instrument panel grd to engine block.

Still no rpm signal

I only have one OEM grounding strap that goes from the top of the driver side engine mount, around to the underside of the same mount.

I'm off to find a bunch of tinned copper straps tomorrow to go batt grd to engine, engine to frame, frame to tub.

At this point, I don't know what else it could be.

Any thoughts?

 

[Belizean]

Bad grounds ( rust ) are just about as bad as no ground. I have a Holley sniper so no real help on Howell. But I keep learning about it. Latest is you need a well charged battery. Having over 12 volts was fine starting up, but it would just die from LV, but would crank back up. Just something to keep in mind. Thinking i have about 4 ground straps.

 

[John Casey]

Update - We got a stumble by spraying brake cleaner into the TB, but wouldn't run.

I went through the Davis DUI troubleshooting instructions, except for the last step which was to take the ignition module to a shop that had load testing device. Nobody in my area has such a tester.

I found on a bench test procedure online for ignition modules using a multi-meter. I used my Klein CL800.

The new GM replacement module (SMP unit from NAPA) was bad in the box. Returned it.

Put the Dyna Mod unit back in that came with the Davis DUI and grabbed a spare champion 71 spark plug to visually inspect the spark while cranking.

Spark was weak.

Verified good ground at DUI to block.

Did the bench test on the Dyna Mod, and numbers were on the high side, but not ideal as per the SMP unit.

Called Performance Distributors, talked to two guys in tech, they are sending another dyna mod unit on spec.

Started seeing a bunch of recurring things online discussing counterfeit spark plugs in the market. As high as one third of the plugs tested in some cases.

According to the Googles, k Ohms for the Champion 71s should be 3-10. The one we used was 26. I then checked another new 71. It was 28. I then check 2 old used 71s, and they were 17 & 18.

Since I had been buying my plugs through Amazon, I check the 6 X Champion 82s (RFN14LY) in the Jeep. They should be 6-15 based on what I found online. This picture is what I found.

This tells me I have 8 bad plugs with 2 different model numbers.

Anyone experienced with testing plugs like this? Legit method? Very strange.

 

[Belizean]

Doesn’t surprise me. Read the same thing about Bosch O2 sensors after getting a bad one for less online from eBay. Box looks legit but ran bad for my sniper efi. Got one from napa and it ran well.

 

[Jeep Soup]

I DON'T use Champion Plugs..
Spend some of that "First Communion Money" you still have, and buy some Autolite, NKG, or Better Grade Plugs.

My Nickel.95

 

[Belizean]

I have a friend a few years back convince me to use Autolites.

 

[John Casey]

Autolite 985s are arriving today at the local NAPA.

A friend also found 6 Champion 82s through Carquest stamped in USA 99. They should be safe.

BTW I just read Autolite is going out of business.

First Brands Group Commences Wind Down of North American Brake Parts Inc., Cardone, and Autolite Business Units

 

[Jeep Soup]

Just a Heads Up,
"Cardone" is a Chinese Parts
JUNK QUALITY remanufacturing/rebuilder
with NO WARRANTY for anything they list!! And some had problems returning parts that were Not Even Close to the correct Vehicle!!

Thank You for the Heads up on the Other Manufacturers listed
Under First Brands.
My only other contact years ago was First Brands was a Medical Supply Distribution Company.
I will check this out with my local parts house on the Automotive supplies.

 

[John Casey]

Still waiting for the new module for the DUI, but here are the new plugs.

Champion 82s on the left with k ohms numbers from a Klein CL800 on the top, and Craftsman multimeter on the bottom.

Autolite 985 on the right. According to what I can find online, Gemini, and Perplexity, the Champions are bad. Again.

Autolites are right where they should be.

So...I've gone through 2 X Champion 71s and 12 X Champion 82s that are bad right from the box.

Does anyone disagree with this test standard?

 

[Belizean]

It’s a new one on me, but I don’t get out much anymore. Unless dropped I always thought they were good. Guess I’m going to start checking with my free HF multimeter. Been meaning to get a new one.