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Could someone please help me?

OK guys I am hoping someone can help me. I purchased a very clen modified

89 Jetta GLI 16V about four months ago. Modifications are as follows lowering springs with Bilstein struts front/rear, front/rear strut tie bars, K&N filter, high perf 10mm plug wires(at least they look like 10 mm) The mods were done when I bout the car. Well taken care of and low miles for the age. However I am slightly stumped on an adjustable relay that is under my hood. Two wires run to the coolant temp sensor, one wire to the the throttle switch WOT I am assuming, but could be the TPS. Now on this relay is an adjustment screw???? What is this for and what does it do. I have made some adjustments to it in hopes to better tune the car, and to me it feels like it delays wide open throttle. I do not know about any internal mods to the motor. I would be greatful if someone could shed some light on this for me. Thanks, John
Reply to
J M via CarKB.com
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Are you referring to the two switches on the Throttle Body? AFAIK they are two switches that will send info to the ECM that either the engine is at Wide Open Throttle or Closed Throttle or Part Throttle. It might be the someone has wired the Coolant Temperature Sensor to give false readings to the ECM that the engine has just been started and needs to run richer. just guessing later, dave (One out of many daves)

Reply to
dave AKA vwdoc1

Quite intriguing. Any chance you could post pictures of this adjustable relay contraption somewhere? A (very) wild guess on my part is that the circuit is intended to simulate cold engine when the wide open throttle switch is depressed, thereby enriching the mixture even further than what the WOT switch does by itself.

Reply to
Randolph

My guess is that it tricks the ecu by disconnecting or short the coolant sensor when you are on full throttle to richen the mixture.

SFC

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Reply to
SFC

Your car doesn't have a throttle position sensor, it has two switches, one for WOT and one for idle. Assuming its CIS-E (not CIS-E Motronic), which it should be, it should be a three terminal connector.

My guess is, its a very cheasy fuel enrichment device (ala Techtronics style). Basically, when your WOT switch is closed (i.e. you are wide open throttle), the relay closes and a resistor is put in parallel with the coolant temp sensor which lowers the apparent temperature. Most likely the "resistor" is actually a potentiometer and so you are adjusting the resistance in parallel with the CTS. When the resistance goes down the car runs open loop, and enriches the mixtue with the differential pressure regulator.

You can pretty easily test this theory. Turn the ignition on, and then go to WOT (by hand). You should hear the relay click. Measure the resistance across the terminals of the CTS wires with the WOT switch closed. Try adjusting it, and see what happens to the resistance.

Volkswagen and Bosch already saw fit to do something like that, directly in the ECU. If you are at WOT and above 2500 rpm (I think) it kicks in. The problem is if you do it based only on WOT you will bog down and over- enrich at low speed. Autotech made a similar device but it has a tach in it and only enriched above a certain speed (also user adjustable).

If you have CIS-E Motronic you can probably do all this with a chip instead of monkeying around with these kludges. I'm not sure how much positive impact one of these could have on a stock vehicle. If you have an aggressive cam, a turbo, perhaps even a 2L block, it might be useful though.

dan

Reply to
dan

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