low speed sluggish and rough idle, HELP!!!

[browning]

Ive had my 86 GN for ten years now and have yet to figure out this problem. The car does not die at idle or in drive. When u take off it is sluggy @ first and jerky at low speeds, up to about 50 mph or so. When u turbo up or floor it, the thing comes alive and runs really strong and smooth. I have replaced over the years MAF, plugs/wires, injector wiring harness.

When I start the car, it spits clear water out of the exhaust with black (carbon looking) spotts on the floor. The fluid is not antifreeze or gas, it is clear and odorless.

I read in "Chiltens" that it could be caused by the EGR. It told me to test it by idiling engine, disconect vacc line, and connect a vacc pump and put 10" on the EGR alone. If the engine idiled alot rougher the EGR is ok and it did. While the Egr was disconnected i put a vacc guage on the line off of the "pulsating vaccum emiter?" and it never moved. I reved up the eng and nothing, does there need to be torque on the eng for it to work? Chiltens had a small paragraph on this thing and it was uninformative and didnt even tell how it worked... I averaged 16 to 20" of vacc on the supply side. 16 at idle and 20 while it was reved up. Someone PLEASE help me make "Scoot" run smooth and efficientley!!!

P.S. The electric fan kicks on befor the eng seems to be totally warmed up. Totally factory car, no mods.

 

[berserker6]

congrats on your first post. now put all your modifications in your signature. it will help in diagnosing your troubles. do you have any scantools?

 

[Hacksaw]

The sensor and engine controls are listed here:

86-87 Turbo 3.8 Liter Engine Sensors

The EGR is the round plastic & metal can, with only one vacuum line on it, that points at the firewall. If you start up the engine, and put vacuum from that pump on the EGR, then the engine should idle rougher, or die. If no change, then the EGR passages in the intake manifold are likely plugged up, or the EGR valve diaphragm is leaking. If you see the shaft of the EGR valve move as you add vacuum to the EGR, then the EGR diaphragm is OK.

does there need to be torque on the eng for it to work?

No, the EGR should activate at idle with vacuum on it.

The EGR is turned off at WOT anyhow, so if it's plugged or the valve is stuck closed, then it will run fine when you get on it.

Diagnostic code checking is here:

Malfunction Codes Reference

 

[XLR8]

When u take off it is sluggy @ first and jerky at low speeds, up to about 50 mph or so.

Does this happen all of the time or when warm? It could be a sticking TCC solonoid not unlocking your torque converter.