Sun 29 Jun 2008 17:26 96 1.9DT vacuum idle control problem - vuk

Just bought a 1996 406 1.9TD executive. All was well for 2 days. The idling speed is all wrong which is controlled by the vacuum. no vacuum = fast idle, vacuum on = warm idle (900rpm~) After it warms up there is no vacuum to slow it down. It does function though, when i rev the engine the vacuum comes on, and then off at 1500rpm or less. IE it thinks the engine is COLD. I guess it is controlled by a temp sensor? If so what sensor? I hope you understand what i mean Please help! Thanks Edited by Pugugly on 29/06/2008 at 18:47 Reply | Report as offensive | Link

Sun 29 Jun 2008 17:48 96 1.9DT vacum idle control problem - Screwloose

vuk Loads of weird systems on those early 406s. Is this the "no ECU" Lucas pump? When you follow the vacuum hose back from the idle capsule; where does it end up? Reply | Report as offensive | Link

Sun 29 Jun 2008 18:03 96 1.9DT vacum idle control problem - vuk

there is only 1 system, bosch pump, bosch ecu on 1.9, on 2.1 lucas pump. it ends in like a little electric switch which opens/closes the airway. hope it helps? Reply | Report as offensive | Link

Sun 29 Jun 2008 18:30 96 1.9DT vacum idle control problem - Screwloose

The 1.9 DHW was a Lucas pump. If you have a Bosch; is this a DHX or a D8B? The idle soleniod should read around 28 Ohms disconnected and have a 12 volt feed on one pin of the [blue?] plug at key-on. The other one is earthed by the ECU when needed. Reply | Report as offensive | Link

Sun 29 Jun 2008 18:35 96 1.9DT vacum idle control problem - vuk

it is a DHX engine. Suppose there is a 12V live on the plug, what would cause it to not lower the revs? Thanks Reply | Report as offensive | Link

Sun 29 Jun 2008 18:47 96 1.9DT vacum idle control problem - Screwloose

Duff solenoid, or the ECU not telling it to operate. [Or no vacuum on it's feed pipe.] However; no point in speculating - test and progress. Reply | Report as offensive | Link

Sun 29 Jun 2008 19:05 96 1.9DT vacum idle control problem - vuk

BUT as I said the whole thing does work, when i rev the engine above 1500, the valve opens and it works, but when it falls below 1500rpm the valve closes and fast idle back on. I will test all just to make sure. BTW: the air con compressor stopped working (engaging) at the same time? related???? Reply | Report as offensive | Link

Sun 29 Jun 2008 19:19 96 1.9DT vacum idle control problem - Screwloose

While you in there; check the coolant temp sensor on the gearbox end of the head: [green plug] 2,500 Ohms cold; 250 hot. Reply | Report as offensive | Link

Mon 30 Jun 2008 20:09 96 1.9DT vacum idle control problem - vuk

reads 250 @90C any other ideas? Reply | Report as offensive | Link

Mon 30 Jun 2008 20:14 96 1.9DT vacum idle control problem - Screwloose

Have you checked the actual vacuum level at the solenoid? Is the valve closing; or is there no vacuum available? What happens if you bridge the valve out with a piece of brake pipe? Edited by Screwloose on 30/06/2008 at 20:16 Reply | Report as offensive | Link

Mon 30 Jun 2008 23:31 96 1.9DT vacum idle control problem - vuk

The vacum comes from the brake vacum hose and there is lods of it, the valve shuts and opens fine at above 1500rpm. on the blue plug there are two red wires, i unpluged it and tested, no V showing and anything of any kind but when pluggen in the valve operates. pic of the vacum valve: img507.imageshack.us/my.php?image=dscf0029copydt6....g hope it helps? Edited by vuk on 30/06/2008 at 23:32 Reply | Report as offensive | Link

Mon 30 Jun 2008 23:53 96 1.9DT vacum idle control problem - Screwloose

There should be 12 volts with the key on. Fed from terminal 13 on the combo relay. Reply | Report as offensive | Link

Tue 1 Jul 2008 17:53 96 1.9DT vacum idle control problem - vuk

Sorry stupid MAPLIN multimeter gave wrong readings. It gets 9V before 1500rpm and 14V after. Also the air con compressor does not engage below 1500rpm related? Thanks! Reply | Report as offensive | Link

Tue 1 Jul 2008 19:08 96 1.9DT vacum idle control problem - Screwloose

Wiring fault. Should be nominal battery voltage all the time the key is on. There's an in-loom joint between wire 1287 that leaves the combo relay and wire 1252 that feeds that solenoid. Reply | Report as offensive | Link

Tue 1 Jul 2008 19:39 96 1.9DT vacum idle control problem - vuk

where is the "combo relay" exactly and how do i know the wire numbers? Sorry but i am not as clever as you are... obviously lol Reply | Report as offensive | Link

Tue 1 Jul 2008 19:52 96 1.9DT vacum idle control problem - Screwloose

In the box with the ECU; often brown, rectangular 15-pin plug, sometimes has "Bitron" on it. Reply | Report as offensive | Link

Wed 2 Jul 2008 07:45 96 1.9DT vacum idle control problem - vuk

sorry my bad, i tested only with engine ON. Engine OFF key ON: 13V Engine ON 1500RPM: 14V I cleaned up all the plugs/connnections. Can't spot any obvious loom damage. Any ideas? Reply | Report as offensive | Link

Wed 2 Jul 2008 13:17 96 1.9DT vacum idle control problem - Screwloose

Still not the correct reading; unless the solenoid is dead short and getting hot, a volt drop like that can only be bad wiring. Reply | Report as offensive | Link

Wed 2 Jul 2008 13:29 96 1.9DT vacum idle control problem - RichardW

Are you sure you haven't mixed the EGR and fast idle solenoids up - the pulling in/out at 1500 rpm sounds rather like the behaviour expected of the EGR solenoid. Edited by RichardW on 02/07/2008 at 13:29 Reply | Report as offensive | Link

Wed 2 Jul 2008 13:47 96 1.9DT vacum idle control problem - vuk

Im sure cos the egr plug is green and the wire is twice as long. Reply | Report as offensive | Link

Wed 2 Jul 2008 14:28 96 1.9DT vacum idle control problem - Screwloose

Richard The significance of that may be that the EGR solenoid is the other spur off that in-loom joint....... vuk Disconnect the EGR solenoid and re-test the voltage at the idle valve. Reply | Report as offensive | Link

Wed 2 Jul 2008 15:52 96 1.9DT vacum idle control problem - vuk

Disconected. Same Reply | Report as offensive | Link

Wed 2 Jul 2008 16:07 96 1.9DT vacum idle control problem - Screwloose

With all three plugs disconnected and everything off; measure the resistance between wire 1287 at the EGR plug to pin 13 of the relay plug and wire 1252 at the idle solenoid to the same. Edited by Screwloose on 02/07/2008 at 16:09 Reply | Report as offensive | Link

Wed 2 Jul 2008 21:23 96 1.9DT vacum idle control problem - vuk

1287 to pin13 0.04ohms 1252 to pin 13 0.03ohms hmmmm Reply | Report as offensive | Link

Wed 2 Jul 2008 21:34 96 1.9DT vacum idle control problem - Screwloose

That's not going to work then. You'll have to measure the voltage difference between pin 13 and the two solenoid plugs with them all connected and working. Edited by Screwloose on 02/07/2008 at 21:37 Reply | Report as offensive | Link

Wed 2 Jul 2008 22:06 96 1.9DT vacum idle control problem - vuk

Right, engine ON, everything plugged in. PIN 13 TO 1252 @ 1500RPM= 14V PIN 13 TO 1287 @ 1500RPM= 0.00V I don't know what to make of this? Reply | Report as offensive | Link

Wed 2 Jul 2008 22:18 96 1.9DT vacum idle control problem - Screwloose

You're measuring both ends of a, supposedly continuous, bit of wire. If you get any voltage difference; then it's got a continuity problem. Find the point that the two numbered wires join; it'll be corroded. Reply | Report as offensive | Link

Wed 2 Jul 2008 22:31 96 1.9DT vacum idle control problem - vuk

What if I run a new wire from PIN 13 to 1252 AND 1287 for testing purposes, will it work? Also btw at pin 13 there are 2 red wires leaving the terminal. Could it be that thats where they are jointed? Reply | Report as offensive | Link

Wed 2 Jul 2008 23:01 96 1.9DT vacum idle control problem - vuk

if one wire from the idle valve plug ends at pin 13, where does the other one end? Reply | Report as offensive | Link

Wed 2 Jul 2008 23:35 96 1.9DT vacum idle control problem - Screwloose

vuk Yes; that would work; but be cautious - no fuses in these circuits. They may split at the relay; PSA wires aren't identified by colours, they have tiny numbers printed on them every six inches. [It's not unknown for them to be blue at one end and red at the other...] The other wire from the solenoids is earthed by the ECU whenever it wants to switch them on. Reply | Report as offensive | Link

Thu 3 Jul 2008 06:47 96 1.9DT vacum idle control problem - vuk

I have to appologise, last night I was rushing and the results are not right. I have just re-checked everything, the 12V feed from the realy at pin 13 sends 14V all the way down to both plugs fine. Continous 14V at any engine speed. However the 2nd wire at the plug is not EARTHED untill 1500rpm. What would cause the ecu to switch so late? Reply | Report as offensive | Link

Thu 3 Jul 2008 15:22 96 1.9DT vacum idle control problem - Screwloose

They will be 14v there if not under load. Are all the previous test suspect too? As to why the ECU does what it does; I don't have access to the intricacies of the software. Is the solenoid piped correctly? Reply | Report as offensive | Link

Thu 3 Jul 2008 21:59 96 1.9DT vacum idle control problem - vuk

NEWS! I have been to many garages today and auto electric places and the best they could do for me is plug it in a diagnostic computer. Very soon I relised they are just wasting my time so I gave up on them and decided to compare my car to another one like it. On the 2nd car the air con comes on at any revs and the voltage at the idle valve is 14V <1500rpm and then 9V there after. So mirror effect from mine. For some reason I thought the throtle position sensor might be to blame. I disconnected that sensor (top of the pump lever) and the air con stopped and the voltage went from 14V to 9V! I have fitted another throtle positioning sensor on my car and now the air con works but cuts out briefly sometime and the voltage is the same just goes to 14V lower in the revs. I guess the wiring going from the FPS might be to blame. Now all i need is a damn wiring diagram to trace the wires :( Help Screwloose? lol Reply | Report as offensive | Link

Thu 3 Jul 2008 22:51 96 1.9DT vacum idle control problem - Screwloose

So now we're back to 9 volts again?? So the 14v of last night is now the mistake? I'm losing track here. The solenoids' feed circuit is as stated. The A/C clutch is switched by the cooling control module [another Bitron relay unit] and has no connexion at all to that solenoid. The fuel lever position sensor has three wires; sensor pin 1 goes via wire 1379 to ECU pin 19; pin 2 wire 1378 to ECU pin 2 and pin 3 wire 1377 to ECU pin 1. Reply | Report as offensive | Link

Thu 3 Jul 2008 23:20 96 1.9DT vacum idle control problem - vuk

sorry its hard to expain, pin 13 wires send solid 14v signal, if I use battery neg terminal and not the neg pin in the plug. If the measurment is taken from the plug it slef its 9V then 14V. So wire 1252 has no problems. Its the NEG one that ecu earths that changes? The (correction) fuel lever position sensor does affect the A/C (quadruple tested), obviously its not directly connected but the sensor, but the data might be used by the A/C ecu. I will check out the loom tomorrow. Also where did you find the wiring diagram cos I cannot find it anywhere. Thanks a lot Reply | Report as offensive | Link

Fri 4 Jul 2008 16:31 96 1.9DT vacum idle control problem - vuk

UPDATE! The car is fixed! Or to be exact it was fixed yesterday. The fuel lever positioning sensor was to blame. The reason why yesterday the revs were not right is because I had the A/C on. When A/C is off the valve operates bringing the engine speed to warm idle. When A/C is ON the valve is off (fast idle position) due to the strain on the engine from the compressor. Also the fuel lever positioning sensor tells the engine when its under heavy load. The A/C switches off briefly when engine is under heavy load (below 2000rpm) to help the car speed up and then is switched on after that. When the fuel lever positioning sensor is unplugged the simptoms return. Thanks to Screwloose and others who helped me Reply | Report as offensive | Link