Surging

ddouglas77 · #1 (**permalink**) 12-20-2006, 09:20 PM

For some reason, my car has been surging like crazy and I need some help on this. There is no vacuum leak, I sprayed around all rubber boots, vacuum hoses with some ether and there was no change in rpm as ether would have caused. If anyone has any info on this and I can tell you it is under load, not at idle. I hit the gas and it takes off real slow and then it just zooms like I hit a nitrous switch. Only does this when engine is warmed, so I'm kindda wondering if this is the ecu or something related....Please help.

ccg498 · #2 (**permalink**) 12-20-2006, 09:40 PM

Without knowing much of anything concerning whatever might have an ECU I would venture a wild guess. A cold start system failure, loose connection, bad sensor for air or fuel?
I would imagine, fanciful perhaps, that a bad Brain/ECU is terminal, nothing, no start, no go, nothing. But some form of 'go' indicates a failure in some part of the info being fed into the brain like fuel pressure, air density, baro, O2, temp... I dunno really, maybe try a post to the Carb/FI section?
Cheers
Sam

alfhole · #3 (**permalink**) 12-20-2006, 11:34 PM

Have you checked your coil and plugs?

Remember to backtrack any mods!

**ghnl** · #4 (**permalink**) 12-21-2006, 05:35 AM

It'd help to know what model Spider we're discussing. You mention an ECU so I'm guessing Bosch - either L-jet or Motronic.

Most common problems with Bosch FI cars are either air leaks or bad grounds. This link has all the info you need (the pictures are not of a Spider but the info applies). http://www.hiperformancestore.com/L-jetronic.htm

Quote:

Originally Posted by ddouglas77

I sprayed around all rubber boots, vacuum hoses with some ether and there was no change in rpm...

Tifosi · #5 (**permalink**) 12-21-2006, 05:46 AM

A quick peek at the printed 'official' L-jet troubleshooting guide in regard to poor throttle take-up lists the following items to check in the order given:

Ignition (including battery voltage, coil, dizzy, plugs and both flywheel sensors)

Hoses and lines (including pressure regulator and pumps)

AAV (to make sure it's closed when engine is up to temp)

AFM (connections and flap free movement)

Temp sensors 1 (in AFM) & 2 (in head)

Vacuum leaks

If I had my druthers, I'd be looking to timing/ignition, fuel pressure & fuel volume and false air.

Mikes4C1300 · #6 (**permalink**) 12-21-2006, 06:23 AM

I'll make a suggestion that was effective with my L-Jet equipped '81 GTV6. It developed a part throttle surge when warm and my mechanic at the time suggested adding fuel injector cleaner to the gas. That might be your problem, too. Try a bottle or two of Techron. It worked in mine although it had a habit of returning to the surging condition a month or two later. (I probably should have pulled the injectors and had them professionally cleaned.) It's only a few dollars and worth a try.

Mike Hollinger
Atlanta

ddouglas77 · #7 (**permalink**) 12-21-2006, 09:34 AM

Thanks for the help! It is motronic and it was the coil wire I put in. It seemed to wiggle loose from the coil, not out, but loose. I splayed the brass terminal out to provide a tighter fit and that did the trick...not sure why it would only act up once the engine was running, but as mentioned, the cold start function of the ecu may have made it less noticable through the IAC.