Weird hesistation in 74 CSi--any ideas??

[Dan Ho]

Hello coupe fans!

My somewhat modified 74 CSi engine (mild cam, high cmpression pistons) has suddenly developed a hesitation under load. It will rev well up to redline if throttle applied lightly but if you really get on the throttle, the engine starts cutting out over 4000 RPM. The problem somtimes gets worse, with the engine starting to hesitate at lower RPMs too. Fuel pressure and airflow are apparently fine as is the remaining ignition system (all have been either checked, replaced or rebuilt in an attempot to fix problem). The only solution my mechanic is proposing now is replacing the trigger points. I can only source a used pair of these but am also worried that they are not the solution. I was told that trigger points either work or do not work.

Thx for any suggestions you can offer re what the problem may be and where I can get new trigger points quickly (if indeed needed)!

Dan

 

[x_atlas0]

I don't know, that sounds like a bad coil or the dizzy isn't set up quite right.

 

[pj]

I had the same thing with my modified coupe , we ended up advancing the timing (alot) and now she runs like a scalded cat. You do end up with a higher idle though.

hth
PJ

 

[coupeking]

I had a similar problem with a late '73 CSi I once owned. Missing that never went away despite $$ thousands of new parts--injectors, trigger, pressure feeler, brain transplants. Everything. Finally discovered that the loom/harness for the ECU brain was not well connected at the right front framerail where there is a fitting that splits it into a front and back half. By improving the connection at this site, I was able to cure the problem.

If you have access to a second ECU for the D-Jet, it would also be worth a trial/test replacement to see if that cures the problem.

ps/ck

 

[coupe74]

hesitation

I have the same problem in my CS but with an M535i 3.5L transplant. It's been driving me nuts for a couple years. I did notice a little crimp in a copper fuel line by the gas tank which will be my next replacement target.

 

[Malc]

Check/change the coil first, a relatively cheap and easy step.
Friend had the same problem on a 250BHP Saab900 FPT with all the trent saab toys.
we changed everything :roll: distributor, MAF, pressure regulator, fuel pump, plugs, plug leads, TPS etc etc etc and still it would hesitate, cut out, lurch, except on a very light throttle

THe last thing we changed was the coil after 2 days of futzing about

Now goes like stink
Malc