1984 633CSI with chipped 0261-200-008 hesitates above 75F

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Moon-Man
Posts: 35
Joined: Mon Feb 20, 2017 10:22 pm
Location: Barrington, Illinois

1984 633CSI with chipped 0261-200-008 hesitates above 75F

Post by Moon-Man »

1984 633CSI 5 spd is showing an odd problem when I try to use the chipped ECU above 75F.
With the standard 0261-200-008 ECU, there are no issues at all that I am aware of, regardless of ambient air temperature. Idle is good. Acceleration is smooth.
When I swap in the rare 0261-200-008 ECU with the chip holder (with Dinan chip installed), I have noticed the following:
1. At temps below ~70F, there are no issues at all that I am aware of. Like the std ECU, idle is good, and acceleration is smooth and strong.
2. At temps above ~75F,
a. Idle is fine.
b. I get what appears to be random injector cut-offs when not at idle.
c. The cut outs seem to happen more when I just left off the gas pedal, and also when accelerating, but not always.
d. The Cut-outs are pronounced hesitations, as if the engine is shutting off and immediately turning back on.
e. AFM is brand new. NOS and in the original box. I still have the old one, and it worked just fine.
f. Fuel pump and fuel filter are brand new Bosch ~ 1500 miles ago.
g. Fuel pressure is right on target. I have an inline gauge in the engine compartment.
h. New silicone vacuum lines.
i. TPS clicks when it moves off/in to idle.
j. The chipped ECU was inspected by Fuel Injection Corp and after fixing a few questionable solder joints, it performed per OEM specs.
k. FIC suspected the chip, so the new Dinan D900-3511 chip has been changed out again with another new one. (Yes, I now have two of them.)
l. It does the same thing with the resistor in and the resistor out of the CTS wire to the ECU.
m. A new CTS was changed out with a new CTS.

Does anyone have any experience with this kind of oddity?
Moon-Man
Posts: 35
Joined: Mon Feb 20, 2017 10:22 pm
Location: Barrington, Illinois

Re: 1984 633CSI with chipped 0261-200-008 hesitates above 75F

Post by Moon-Man »

I typed the chip number wrong, it is a D900-3311,not a 3511.
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Brucey
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Re: 1984 633CSI with chipped 0261-200-008 hesitates above 75F

Post by Brucey »

I suspect that the ECU may have some dodgy joints in it still, or that there is a basic ignition system fault of some kind. I'm not sure how to best to check it exactly if the fault only happens under load but if you can check for spark/injector function during the fault that would be a start. Needless to say if you can fit a standard chip to the 008 ecu this will tell you if the ECU or the chip is at fault.

If you have not changed them, a new set of HT components would be a good idea; (if you don't really need them you have some spares and that is never a bad thing). You would normally get a misfire rather than a hard cut if the HT system is a bit iffy, but firing the plugs at high cylinder pressures and with the correct mixture strength (which is what you are trying to do with the engine warmed up and fitted with a performance chip) is more difficult than otherwise.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Moon-Man
Posts: 35
Joined: Mon Feb 20, 2017 10:22 pm
Location: Barrington, Illinois

Re: 1984 633CSI with chipped 0261-200-008 hesitates above 75F

Post by Moon-Man »

Thanks for the suggestion. I have not yet tried the chipped ECU with the stock chip that it came with.... that will tell decisively if it a chip prob or not. Maybe this weekend!

The cap, plug wires, rotor, & plugs are new as of ~1500 miles ago... Coil is original though, so probably worth updating after trying the stock chip swap.

14.7 is challenging for sure!
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