Know this should be in the tech section, but prefer to deal with the local crowd!
I have a '89 305 TPI auto unit, in my '84 Mecham with a complete swap no mods. My problem is that recently the car runs great until it gets hot (not overheating), or if I turn it off then start back up. Seems as though # 5 and #7 cylinders are not firing after getting hot, after it cools it runs fine again. No SES lights either, just not running good. Any ideas? Anybody run into this problem? Thanks for any help.

 

Check the ohm readings on the injectors when the car is hot. Sounds like maybe a couple of bad injectors. Did you reuse the originals when you did the swap?

 

I was going to guess injectors too. You can also rent a set of 'noid lights to see if each injector connector is firing.

 

Injectors do not tend to get or cause alot of heat... I would be looking at coil or cat

 

The car is not running hot. It just runs poorly when it warms up.

 

Then why dont you bring it by the shop... We do diagnostics for 40 bucks.....
Automotion its just north of Bell on 19th ave. the address is 17219 N 19th ave its right next to the car wash across from the sonic

 

POSSIBLE IGN MODULE FAIL WHEN HOT. I HAD ONE DO THAT LAST YEAR. CHECK CONNECTION INTEGRITY ON SUSPECT INJECTORS PLUGS. AND ALL CPU GROUNDS AND SENSOR PLUGS CONNECTIONS AS WELL. MAF / IAC / MAF RELAYS / BURN - OFF / FUEL PUMP / MAF WIRE IS CLEAN

 

I did use the original injectors, at the time the system was running perfect. Thanks for the suggestions. I will try some of those ideas and get back. Thanks again!

 

ALWAYS GO FOR THE SIMPLE FAST STUFF FIRST SO YOU DONT WASTE YOUR TIME . LIKE LOW CHARGING SYSTEM VOLTAGE / BAD GROUNDS. IVE HAD THOSE TWO BITE ME IN THE **** MORE THAN ONCE.