Tight fart Posted July 15, 2003 Share Posted July 15, 2003 On a Dunnell Fuel inj Zetec? Link to comment Share on other sites More sharing options...
DohNut Posted July 15, 2003 Share Posted July 15, 2003 I think you will find that you have three wires. the outside two wires attach to each end of the semi-circular resistor the middle wire goes to the sliding contact that moves when you rotate the spindle. The resistance between the outside two wires never changes The resistance between the middle and outers will change due to throttle position. Adding the resistance of each middle to outside resistance should add to the outside to outside resistance. To compensate for length of wire the ECU measures the comparison of the resistance between each "half" of the throttle pot rather than an outright value. I suppose that the thing to check is that it is working roughly to this format. Link to comment Share on other sites More sharing options...
V7 SLR Posted July 15, 2003 Share Posted July 15, 2003 What exactly are you checking for? If it is specification, then you not the max resistance. If it is condition then you have to measure the changing resistance for any "crackling" which may be caused by track damage. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Tight fart Posted July 15, 2003 Author Share Posted July 15, 2003 I'm checking it because the engine is cutting out at around 1800rpm, you can blip the throttle dip the clutch and get the revs up to 3k'ish and it runs fine. I have just finished installing it and all else seems fine. Can't think what else to check. SLR for sale (but not till after Le Sept) *cool*Zetec now running. T.F@O.F. www.griptv.com Link to comment Share on other sites More sharing options...
V7 SLR Posted July 15, 2003 Share Posted July 15, 2003 If you can steadily raise the revs whilst out of gear then it won't be the TPS. If, when you attempt this, it fails to hold a certain revs (1800 as you say) then you may have a problem. If you have a multimeter, check resistance of the middle pin against one of the end ones. I'm assuming the TSP works like any other variable resistor. It ought to read a consistently increasing/decreasing (depending on which way you measure it) resistance. If there's any inconsistencies with the readings then you may have a knackered TPS. Unusual if so. Normally caused by overtightening it against the throttle bodies I believe. Also, it could be a "hole" in your map. What ECU? Do you have the software and cable so you could watch what's happening? Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Tight fart Posted July 15, 2003 Author Share Posted July 15, 2003 I have checked the res. on the tps and it looks fine so I think thats OK. The EMS is one from Dunnells badged as pro-line, (and AAE on the box). I have no details on it, only a wiring diagram. Link to comment Share on other sites More sharing options...
V7 SLR Posted July 15, 2003 Share Posted July 15, 2003 Did you fit it yourself? The balance of my throttle bodies was miiiiiiles out until Karl at Emerald sorted it out. Depends on the story of how the Zetec was put together with the ECU. If it was a pro jobbie then it rules out a lot of the other potential problems such as TSP range not "told" to ECU, mapping irregularities, throttle bodies balance etc... Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Tight fart Posted July 15, 2003 Author Share Posted July 15, 2003 It was put together at Dunnels a while back and not used for a while, all I have done is install it, and connect the loom up. Link to comment Share on other sites More sharing options...
elie boone Posted July 15, 2003 Share Posted July 15, 2003 I would start to clean every elec. connection with WD40 or similar product, corrosion is a common trouble spot on engines that have been out of a car for some time. Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2003 Share Posted July 15, 2003 Doh Nut! To compensate for length of wire the ECU measures the comparison of the resistance between each "half" of the throttle pot rather than an outright value. Not so ............the reason they use 3 terminals is because the TPS is wired as a "potential divider". It has a constant voltage across the end terminals and the middle terminal will be at some intermediate voltage directly proportional to its position. So the ECU knows where the throttle is by monitoring the voltage it receives from the middle terminal. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Tony Whitley Posted July 16, 2003 Share Posted July 16, 2003 Isn't that what Doh Nut! said in a different way 🤔 The ratio of the voltage of the wiper compared to the voltage across the pot is the same as the ratio between the resistance in one "half" of the pot to the resistance of whole pot. But there again I'm a software engineer and look at things differently Tony M1 7 SMW 1.4SS Lotus colours with cycle wings. Back on the road Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now