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Discussion Starter #1
Finally was able to go for a real ride after the winter upgrades and have a random engine loss of power. It happens at any RPM, speed or gear. Engine will suddenly lose power for a split second and then resume (very annoying). Winter mods were removal of the following stock 89HO engine components and replace with a TYPHOON polished upper/lower intake, FMS 30lb injectors, 75mm PRO-M MAM for 30lb injectors, 75mm BBK throttle body and EGR spacer, Aeromotive fuel pressure regulator, re-calibrated Vortech FMU for 30lb injectors, and removed the extensions on the TAD/TAB connectors because not needed (salt & pepper connectors).

Pulled OBD codes and had #67 (neutral drive switch), #31 (EGR valve control system), and #63 (throttle position sensor). Checked/verified the TPS and have .98vdc. Checked/verified the EGR connections and vacuum hookup as it was before the upgrades. Don’t know about the neutral drive switch? Any thoughts on the cause?? Ran OK before the upgrades with no problems or error codes.
Thanks
JimmyZ

[ April 09, 2005, 05:22 PM: Message edited by: JimmyZ ]
 

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Check the TPS. Voltage at closed throttle is only the base setting, not the test that the TPS is good. Get your DVOM out and check it just like you would if you were setting the .998 volts. Now open the TB slowly and see how the TPS reacts voltage wise. It should be progressive and not jump around alot. If you have removed the EGR then disregard the EGR code, if not then it may be stuck open or sticking at some point. Check all the connections and if everything is fine then first make sure the diaphragm is ok but sucking on the vacuum port, if that is good then clean out the EGR valve. If the valve sticks then it can cause loss of power and rough running.

James
 

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The TPS code could be the problem. If you have a dead spot or fault in the TPS (outside of idle) then it could be causing the computer to cut fuel thinking you've closed the throttle. Know anyone you could borrow a TPS from to check it out.

Cheers, Rod
 

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I had the ignition switch do that to me for several months until it finally got bad enough to find.
Marc A
 

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Discussion Starter #6
I will check the TPS to see if I got dead spot or a steady increase. I still have the EGR and it looked clean but I will use some brake cleaner and blow it out with air. I will also check all other connections and ignition switch just to be sure. It's probably something I did during the upgrade as I had a lot of connections (electrical and vacuum) separated.
JimmyZ
 

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Discussion Starter #7
Last night I checked both the TPS and EGR components. Removed power to the computer to get rid of the error codes. First I checked the TPS for dead spots and did not find any after numerous attempts. Next I removed and cleaned the EGR components and reassembled all connectors with dialectic grease. This morning I went for a ride and almost immediately I had the random engine loss of power. As I was returning home I started to think about things I did and what could cause this. I remember quite a few posts about the sensitivity of the TAB/TAD (salt & pepper) connectors. I did remove the extensions that were a factory recall. Removed power to the computer to reset any error codes. Removed the black connector and on the male portion there is a red O-ring on the inside that was jammed down between at least three of the pins. Moved the O-ring back to where it belongs and cleaned both connectors with brake cleaner and compressed air and added dialectic grease and reassembled (white connector O-ring was OK). Went for a ride and NO random engine loss of power. Put about 50 trouble free miles on it today. Felt GREAT!!
JimmyZ
 
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