Chronic idle problems now solved !

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glasgowjim
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Chronic idle problems now solved !

Post by glasgowjim » Mon Mar 14, 2011 8:03 pm

1992 BF18 engine

car had stood for the best part of 4 years with only the occasional run round the block. Then driven 400 miles upto Glasgow , had a number of issues with cooling system fans etc but all sorted one by one then the damn car starts to idle at 1200rpm then 1400rpm.

NOW

it starts and idles at 1400/1500rpm then after a short while driving it idles at 2000rpm yes 2000rpm

so this is what I have done so far:

replaced
IDV with a known 800rpm tickover unit
new silicone ignition leads + HT lead
new dizzy cap
new sparkplugs
new air filter
new lambda sensor.
removed and cleaned the throttle body (was 1400rpm after being refitted it was now 1800/2000rpm
changed over throttle position sensor no joy

when I disconnect the IDV engine tick over slows dramatically.

Can anyone confirm the voltmeter readings for the lambda sensor ?
the resistance values for the throttle position sensor and the engine temp sensor (cold start- above cylinder No 1)

finally does anyone have any more suggestions as I am getting angry at this point with the whole shebang.

daveo2002
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Re: Chronic idle problems URGENT

Post by daveo2002 » Mon Mar 14, 2011 8:28 pm

Funnily enough I was testing my engine temp (cold start) sensor this evening. Stone cold it read 6700 ohm and after 15 minutes warming up that had dropped to 540 ohm. Broadly similar to Iroll's results here:

http://www.thelair.org.uk/forum/viewtop ... 11&t=18852

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Re: Chronic idle problems URGENT

Post by Iroll480 » Mon Mar 14, 2011 10:41 pm

looks like the ICV is getting the wrong input from the ecu. If you pull the connector the ICV closes and the rpm lowers, Am I correct? If so it must be the culprit, the ecu keeps the ICV fully open. Maybe some short in the wiring from the ECU or it's connector? The readings for the lambda are in the howto section from Aibast iirc?

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glasgowjim
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Re: Chronic idle problems URGENT

Post by glasgowjim » Tue Mar 15, 2011 12:16 am

changed ecu and it made no difference .

are you certain about the icv ?

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glasgowjim
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Re: Chronic idle problems URGENT

Post by glasgowjim » Tue Mar 15, 2011 12:18 am

Oh I should mention that there is a rattle from the exhaust.

and when you accelerate the engine has a very slight stall.

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volviz
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Re: Chronic idle problems URGENT

Post by volviz » Tue Mar 15, 2011 6:58 am

you should check on ignition timing, maybe belt has sliped few teeth.
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glasgowjim
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Re: Chronic idle problems URGENT

Post by glasgowjim » Tue Mar 15, 2011 7:47 am

Oh I did one thing between the 1400 rpm and the 2000rpm I took the throttle body off and cleaned it and reassembled it then everything went wrong.

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Re: Chronic idle problems URGENT

Post by Iroll480 » Tue Mar 15, 2011 8:54 am

Maybe an airleak from the throttle body, did you use a new gasket? Is the Thr.pos.sensor adjusted according the "click" method? With the slightest opening of the throttle you should hear the TPS click, that is the right position. Sure that no solvent entered the TPS while cleaning the thr.body? Throttle cable not too tight adjusted, should have some slack.

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volviz
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Re: Chronic idle problems URGENT

Post by volviz » Thu Mar 17, 2011 7:25 am

recheck all vacum lines on intake, throttle body - backing up idea that engine is getting extra air in.
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glasgowjim
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Re: Chronic idle problems URGENT

Post by glasgowjim » Wed Mar 23, 2011 7:38 pm

problem solved now idles at 800rpm and runs sweet as a nut :rofl:

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volviz
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Re: Chronic idle problems now solved !

Post by volviz » Thu Mar 24, 2011 8:08 am

and the problem was....?

P.S. by your posted emotions it was something :nuts:
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glasgowjim
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Re: Chronic idle problems now solved !

Post by glasgowjim » Thu Mar 24, 2011 11:11 pm

A lot of the problem was the advice given by various posts in the past refer to 480 turbos which have a different sized throttle flap and while their TPS click non tubo ones don not.
Also the readings from the lambda sensor are not quite right either.

So in summary replaced

TPS
cold start sensor
throttle body
lambda sensor
changed over IDV (advice given is not correct either.)
changed over the ECU which made a huge difference (and reset it)

and put the connectors in the right place

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Re: Chronic idle problems now solved !

Post by AleksanderHugo » Mon Apr 24, 2017 8:29 am

I have two TPS sensors for the 2.0 engine: one old Bosch and a newer "unnamed". On Bosch the resistance is about 870–2500 Ohm (from closed throttle to fully open). On the unnamed one it is 1100-2600 Ohm.

I have read somewhere that the correct resistance should be 1000-2500 Ohm. Can someone confirm that this is true? What tolerances can be accepted? I am wondering if either of my sensors is usable.

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