Mercury motor rebuilders

[johnboy 88 vegas]

CDM ignitions are nothing but high dollar junk. I went back to the old style ignition after my motor tore up last year and haven't had a complaint since.

[wrechin2]

The only thing I can say about CDM's igniton is that it is a lot neater..........

[TEXAS20225]

James its is a lot neater and very easy to hook it all up. i just dont get that many people in my place with the later style motors i have a box full of carb and Efi parts off late model stuff just dont know how to check it yet i have a DDT and DVA and FLUKE so im sure if i set my hard headed self down and started reading i could figure it out . i have noticed on the CDM motor that they dont rev quite as high as a switch boxed motor 5800 versus 6100 on a 200 efi

[wrechin2]

just went thru this on a friends 260 that wouldn't rev past 6500, he sent the computer out to be tested and it tested fine, yet when he installed a different computer the problem went away

goes back to the old "half assed" troubleshooting deal, "replace w/ known good part", ridiculous

Isn't that the same thing???????????

Some of the overseas car makers has that a lot in thier service manuals as well. I used to work for Dodge and we had Mitsubishi cars with our badges. We had their service manuals and it stated to test with a known good part. If issue goes away replace with new part.

CDI actually makes that kit PN# 511-7509K6 for testing mercury CDM that has the 6 CDM's. Sometimes it is the only way to test if parts test good. I have ran into that on 3 stators that tested "good" and were having a issue with only 1 cylinder. I would have bet big money that a stator could NOT cause a issue with only 1 cylinder. I would have lost!!! You follow the ignition test will condem a switch box because the stator volts are present and the trigger volts are present with no outpout to the coil and turned out to be a stator!! I test and then switch out that part with a know good one to be 100% sure. I got burnt on a switchbox that was shorted. Tested the stator volts and it was 110 volts which indicates a bad stator. I ordered a stator and still the same problem and same volts. Was a shorted switch box!! I now remove the stator wire and retest to make sure it don't happen again. Electricity is not always easy to diag. Just my experiences.

[wrechin2]

Bobby,
You have all the information in the manuals I sent you! Go have fun! LOL!!!

[TEXAS20225]

James i was just reading the late model EFI stuff you sent me you must been reading whats left of my mind i have around 7 or 8 harness that came with my DDT ( i traded for it ) it was brand new a couple of years ago. it has one smart craft chip and a 2.5 chip .One of the bags says CDM test harness on the bag it aint been opened and some other harness i have not even looked in to. I did get 2 TPI test harness one round and one flat i use all the time but not on the DDT i use the fluke for that . If you aint busy Tomorrow after i get out of church i may give you a shout and see if you can tell me how to test for double firing switch boxs i need to know that later BV

[wrechin2]

Not all CDM's use the motorola. There was also a few years of CDM's on the 2.5 that was the old "standard" ECU set up where the injectors fire in a gang/sequential that fires 3 pairs that is totally different from cars. On cars you have a gang that fires the left bank then the right bank using 2 injector drivers. Then sequentially where it fires them in a firing order and has as many injector drivers as cylinders. Mercury "laser" EFI has a combination of gang/sequentially that has 3 drivers for 6 cylinders firing them in pairs. Then the motorola fires sequentially. I have not had to do anything on those and did not know that. I learned something! The ECUs will interchange between the switchbox and early CDM's that don't have the motorola. I got into that when I ported a 01 150hp (yes, a idle relief) to a 200hp. The rest of the EFI system was the same. I simply used a A26 200 ECU on it and runs great with a very happy customer.

There are 2 diffferent pin configurations on the 4 and 5 pin. There is one tool that doubles as a TPS tool (on certain years) and a CDM tester. I made mine from a Dodge IAC (intake air control) connector and a old IAC. I can install it between the CDM and harness and test voltages from the passenger seat. There is charts in that manual of what voltages you should have at the cdm at certain rpms. Look forward to hearing from you!