coolant flowing between iac and isc ?

[john110]

You`ve got so many infos(a great thing), I miss those link.... After reading your text below, I`m wondering if is there a list for this ? "....the ECU under special cruising situations opens the valve..." a list of situations ordering the ECU to open that valve to let Mod and Egr to do their jobs.

Another thing, Last yeat I removed the Cat on my 94 Tracker and installed a strait pipe thinking it wouldn`t change anything. Huhhhh I can now see that it wasn`t such a great idea.

"89-98:
The ECU commands the EGR to open via the Vacuum Solenoid Valve VSV) and then MOD, measures the pressure drop.
The Vacuum port at the manifold is ported and has a varying vacuum to the input of the EGR VSV.
The ECU connects electrically to this VSV solenoid, the ECU under special cruising situations opens the valve and passes this vacuum to the
EGR MOD valve. The Mod valve (aka: transducer in newer Suz. manuals) then modulates this vacuum even more by virtue of the exhaust back pressure.
The output of the Mod valve passes to the MAIN EGR and it opens proportionly to these inputs I have just described.
This is what happens under normal driving. Any Failure sets DTC 51 , for failure of valve to open , close or heat up the thermal probe.
And all 95 and all Calif cars run a thermal probe test.

more.. 89-95:
The MOD valve , only allows vacuum to pass to the EGR valve under limited pressure states in the EGR exhaust port.
( you must have exhaust back pressure!)
Due to that fact, a missing CAT can cause the MOD valve, to fail completely. (missing, rodded-out, blownout,melted, broken up)
* heads up CAT bashers ! I see you with that broom handle. bang, bang.... inside that CAT, you are a naughty boy, your are....!
The results is an engine that runs badly."