Darren Roberts Posted July 29, 2017 Share Posted July 29, 2017 (edited) Hi Guys, I've got a 1992 Hard Dash 3.9 Auto SE, been bobtailed by the previous owner. When buying it I think I recall the owner saying it originally had cats that were now removed. So I have the lamba sensors in it, but no cats (and no back box either). Its running very rich (so much the mrs won't come out in it with me!). I've invested in an ECUMate, it says I have fault codes 14 - water temp sensor and 17 - Throttle pot, it's also saying I'm in limp home mode (ticket about 1500 rpm) and the ECUMate is saying I'm running white tune with cats. This problem seems to have been getting worse since a mate replace the valley gasket for me and I had a new temp sensor, so got him to swap that out at the time. Before I start buy-in new parts, should I also consider putting the correct tun resistor into the loom? Is having the resistor with the tune for cats causing issues because the fuel map is wrong? Or should I swap out the water temp sensor and the other parts first. And when they say throttle pot, do they mean the idle control valve on the side of the plenium, like ERR5322 or is it part of the MAF? I have a spare MAF so is it worth fitting that? Or could it be a wiring issue with the loom into the MAF... thanks in advance for any help...... Edited July 29, 2017 by Darren Roberts Quote Link to comment Share on other sites More sharing options...
Quagmire Posted July 29, 2017 Share Posted July 29, 2017 (edited) If the doodah says you have a knackered water temp sensor then that will definitely make it run rich, so I'd change that as a first step. *Edit- just re-read your post again. So you have changed the water temp sensor and it's still overfuelling? Edited July 29, 2017 by Quagmire Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted July 29, 2017 Share Posted July 29, 2017 Make sure the fuel temp and water temp plugs have not been swopped,seen this done several times... Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 29, 2017 Share Posted July 29, 2017 Yep, also check the wires aren't broken - check the reading of the temp sensor is working at the ECU plug. Hotwire diagnostics in the tech archive. Tune resistors won't make that much difference, certainly won't make it run that rich. But do swap once you have sorted the other issue. Throttle pot is on the plenum, connected to the other side of the butterfly, this has 3 wires going to it. Very common they break off, loadsa money new, find a second hand good one if you can't find a wiring fault elsewhere, again check at ecu plug if seems ok at the throttle pot. Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted July 29, 2017 Author Share Posted July 29, 2017 Thanks guys. Didn't know there was a fuel temp sensor. I've got the old water temp sensor somewhere so I might put that back in and see if that cures the water temp fault.... Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted July 29, 2017 Author Share Posted July 29, 2017 God, Bowie, now I know what you mean about the throttle pot......why did they stop making them? Might be a bit of a bitch to get one of them..... Quote Link to comment Share on other sites More sharing options...
L90-v8 Posted July 30, 2017 Share Posted July 30, 2017 green tune resistors are a job to find I popped to maplin an got a 470 ohm resistor for less than 50p I got the 2 watt one as there easier to handle i had a spare plug kicking around ard soldered it to the existing wires wrapped it in shrink wrap job done Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted August 12, 2017 Author Share Posted August 12, 2017 Update. Today changed the water temp sensor (new) and Throttle pot (second hand un-tested). Same faults still showing although it appears tp be running and sticking over better, Used my ECUMate ti clear the faults, stopped and started the engine again. Same faults came back (14 temp sensor and 17 throttle pot). Not sure what my next port of call should be? Suggestions? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 12, 2017 Share Posted August 12, 2017 Check signal at ecu using hotwire diagnostics in the tech archive. Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted September 17, 2017 Author Share Posted September 17, 2017 Ok, pulled the seat out today, check the ECU connectors for corrosion and sprayed contact cleaner on both sides. Can't figure out how to get the hard plastic cover off the eco plug to get to the wires. I've also noticed that the insulation has pulled off some of them when I pulled the rubber boot back. I noticed one of the relays weren't on their holders, so fixed that at the same time (but managed to earth one and get a spark). Now I have it turning over but no longer running. I'm off to check the fuses next to see if that blew one of them. The black rocker switch under the drivers seat - immobiliser? Should it be in the up or down position? cheers D Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 17, 2017 Share Posted September 17, 2017 From memory of our need to unscrew a collar on the ECU plug? Been a while now, am on Megasquirt Check your fuses, it is likely you have blown one... Rocker switch is non standard, sounds like someone has been fiddling... Try it both ways Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted September 17, 2017 Author Share Posted September 17, 2017 I think I've fried the ECU. Cranking but definitely won't start. Checked all the fuses they're ok. I think it was the loom for the new defund electric seats that arc'd. Ordered a replacement ECU and loom off eBay. AT least I will be able to test the loom before I swap it out...... Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 17, 2017 Share Posted September 17, 2017 Frying the ECU is pretty tricky... Checked the fuses under the passenger seat? Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted September 17, 2017 Author Share Posted September 17, 2017 Under passenger seat? No checked them under the drivers seat. Passenger seat could be a bit tricky because it doesn't run and it's parked with the passenger side up against the garage wall. Are you thinking that maybe the fuel pump Fues has gone or something else? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 17, 2017 Share Posted September 17, 2017 Yup crawl in the rear passenger footwell, and fold the carpet back, you can see and access the fuse box easily then. No need to remove the seat Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 18, 2017 Share Posted September 18, 2017 They're always in the best places! Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted September 18, 2017 Share Posted September 18, 2017 The rocker switch is the inhibit switch for air suspension. There should be 2 silver ish coloured relays together behind the engine ecu.5 pin Bosch ones as standard, one is main ecu load relay which obviously has to be there and work to start the engine.The second is the fuel pump relay which should energise for a couple of seconds at key on to prime the fuel rail.(And energise again when the ecu see's a pulse from the HT) This relay also has a second function which is to feed the heater circuits of the oxygen sensors. If the contacts dont feed the fuel pump it won't start,if they do that,but not the oxy sensor heaters it will run very rich. I saw this many years ago on a Morgan Plus 8 where the fuel pump relay had been changed,but didnt have the fifth middle pin to power the oxygen sensors. Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted September 23, 2017 Author Share Posted September 23, 2017 Thanks AllyV8. Nice to know that the rocker switch is nothing to do with the ECU. Today I pulled a plug - it's getting a spark but not looking wet. Put a jerry can full of fuel in it to make sure that the tank wasn't empty. I've found the relays you've mentioned. I swapped the ecu (black bottom) to the fuel on (blue bottom) but when juggling them about, because they have metal cases on them, they seem to be live when clipping the body. I found some lucas relay out of a previous scraped rangie loom that I have for butchering. I've tried them but to no avail. It cranks, sparks but doesn't fire.... I will check the relays and if necessary buy some new ones....and try again..... Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted November 11, 2017 Author Share Posted November 11, 2017 (edited) Ok, after working away and building work getting in the way, finally a chance to have a look. I've discovered a break in one of the three wires to the throttle pot on the loom side, so I've fixed that. So now I have on one error code - coolant sensor. I no longer have throttle pot (yeh!) and it no longer reports itself to be in "limp home mode" on the eco diagnostics. I've replaced the coolant sensor. No joy. Wired the coolant sensor directory into the eco by scotch clipping two new wires into the wires into the ECU about 4 inches from the big eco connector block - the other end was a bit of loom from an old Freelander that had the right plug for the temp sensor. Still same error. Bit stumped as to where to look next..........what should I look at next? cheers Edited November 11, 2017 by Darren Roberts Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted November 12, 2017 Author Share Posted November 12, 2017 On 29/07/2017 at 6:53 PM, Ally V8 said: Make sure the fuel temp and water temp plugs have not been swopped,seen this done several times... Actually it was the injector connector on the right hand bank nearest the front and the temp sensor. Can't believe it ran like that or that the temp sensor and injector plugs are the same! The boots had splits it made it easier working out the colours were wrong! Thanks for your help guys..... Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted November 12, 2017 Share Posted November 12, 2017 1 hour ago, Darren Roberts said: Actually it was the injector connector on the right hand bank nearest the front and the temp sensor. Can't believe it ran like that or that the temp sensor and injector plugs are the same! The boots had splits it made it easier working out the colours were wrong! Thanks for your help guys..... Well that's another variation on the theme I need to remember.Glad its sorted. Quote Link to comment Share on other sites More sharing options...
Darren Roberts Posted November 12, 2017 Author Share Posted November 12, 2017 thanks. Major hair pulling exercise now over on that front. I had no idea it would ever run like that...... Quote Link to comment Share on other sites More sharing options...
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