Mysterious engine hesitation
 

I recently have a strange problem that I've never seen before, wondering if anyone had any insight?

Every once in a while during acceleration I here a click sound and the engine falls to idle (as if I just let off gas completely) and then goes right back to normal. The trans and clutch are fine, its not slipping out of gear and clutch isn't slipping. It has happened mostly when starting in first gear but has happened in second and fourth. There is no correlation between when it happens and what gear I'm in, what speed I'm going, or what RPMs I'm turning. I've changed cap and rotor recently wires are good. Trans is freshly rebuilt. 1990 RS 305 TBI with WC T-5. Any ideas?

I also have a strange shuttering when I punch the gas when I'm going to slow for the gear I'm in (ex cruising at 40mph in 5th) not sure if related.

Thanks,
Matt

Re: Mysterious engine hesitation
 

Maybe check that distributor module and the coil.

Re: Mysterious engine hesitation
 

Check those, but also check your esc, see if any auto parts places can test it. I had a problem very similar to yours, but slightly worse (it would randomly stall out, shutter, lose all power, and at idle in gear it would sometimes get very powerful, almost overcoming the brakes as if i was trying to do a burnout) and it turned out to be the ESC. I was lucky however, i unplugged mine, plugged it back in and (knock on wood!) havent had a problem since. I guess it just got knocked lose and didnt make good contact. Defenitly something to check.

Re: Mysterious engine hesitation
 

Thanks for the responses, that sounds like a possibility. I didn't even know what the ESC was until I just googled it! Can you tell me where the module is located?

Re: Mysterious engine hesitation
 

Lol sure, Its on the "bulkhead" on the firewall, drivers side, right by the hood hinge. If you dont know what the part looks like i posted a link below

In the corner, there are relays too. The esc is kind below and behind the relays. Its hard to describe where, much easier to point out.

This is what it looks like:
http://www.ebay.com/itm/1985-Pontiac...r#ht_503wt_702

Re: Mysterious engine hesitation
 

my car just started to hesitate today enging and trans are good got 5000 miles on rebuild of both i was ajusting tv cable and drove around yesterday and i no issues everything was fine then i start car today and engine service soon light is on and when i put it in revese car shut of after idling then idle drop and shut off when put into reverse twice after that i warm engine up and i got it out off the parking spot as i was crusing down street the idle was jumping up and down as if i was pumping the gas after i got to a higher speed it idle and drove good till i step on gas and same thing happen and at higher speed it did it again wround same time as trans shifts from 2 to 3rd but at idle at stop light it idles fine it starts fine when i stop from time to time idles dips due to what i believe is a slight vacum leak when applying brakes but ive been driving it like that for a while now and ideas where to start diagnosing 3 days earlier i had put mystery oil in fuel system to clean fuel system but i ran fine for 3-4 days so i assume its not related to that

any ideas?

Re: Mysterious engine hesitation
 

thanks for the info. I tried unplugging it and re-connecting it but I wasn't so lucky it is still happening. I think I may be faced with having to start throwing parts at it. I'm just not sure what could be causing a click that I hear every time

Re: Mysterious engine hesitation
 

I tried changing the coil today and that solved the problem. The click I was hearing must have been large arcing inside the coil

Re: Mysterious engine hesitation
 

Something so simple that makes a major headache solve mines to lose sensor connection on intake had to zip tie due to clip being broke

Re: Mysterious engine hesitation
 

Banks4004 glad that you got it fixed and happy we could help.