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        General >> Problems >> Idle Problems
        
(Message started by: Fidget on Mar 31^st, 2007, 4:56pm)

Title: Idle Problems
Post by Fidget on Mar 31^st, 2007, 4:56pm

I've checked throught he fault finder on the site and still have problems with idle.

My idle speed is fluctuating between 995 and 1012 rpm (and is rough) and the TPS is also flutcuating between 16.9 and 17.3. These are readings with the air con off. If I push the revs to around 2000rpm, then let off the accelerator, the rpm drops tro around 1500rpm for a second then slowly drops back to around 1000 again. Gear change is subsequently 'thumpy'.

If I switch the air con on, the speed drops to near the desired 864 rpm and stays steady when the air con pump kicks in. If I rev up to 2000rpm then release the accelerator, the idle drops swiftly down to the 864rpm again, no problem.

I've replaced the IACV, checked and cleaned MAF and inlet air temp sensor. MAF is reading around 0.56 to 0.6 (with air con off) @ around 0.76v, TPS is reading around 0.85v, IAT sensor is reading 88F at around 2.56v. I've no DTCs. I've cleaned the throttle plates and body to metal with carb cleaner. I've checked for induction leaks and can find none. The car has also recently had a new cat and lambda sensors.

I'm quite puzzled right now and any help is greatly appreciated. I can provide any scan (I have the PWM ISO combo).

thanks in advance.

Title: Re: Idle Problems
Post by Kjetil S on Mar 31^st, 2007, 5:04pm

Still sounds a lot like you may have an air leak somewhere. Try checking for hissing sounds from your EGR valve. You might even try disconnecting the vacuum feed to the EGR valve and block off the ends.

Title: Re: Idle Problems
Post by Fidget on Mar 31^st, 2007, 5:32pm

Thanks for the advice, I've run around all those connections already with a hose in my ear, can't hear a hiss at all, but I will try disconnecting and plugging tomorrow. I might still have some leak detector spray in the shed which I'll look for tomorrow too.

I forgot to mention another problem ...

I get some engine vibration between 15 and 20 mph (1st or 2nd gear) which is not there when the engine is cold. This improved slightly when I replaced the IACV. And the old girl seems a bit flat up to 30mph when it feels like a turbo kicks in.

Title: Re: Idle Problems
Post by Spannerdemon on Mar 31^st, 2007, 7:28pm

My money is on the TPS. Exactly the symptoms that I had.

Unfortunately replacement is the only option. ;)

Title: Re: Idle Problems
Post by TRACEYS_LIMO on Mar 31^st, 2007, 7:39pm

I have found cleaning maf doesnt always work thumpy gears are a bit of a give away, hope this helps :( david

Title: Re: Idle Problems
Post by scorpio_man on Mar 31^st, 2007, 8:04pm

hi there

don't like the MAF figure, a bit high. if you send me the scan (the 3 files), i'll have a look at it for you.

hth

Title: Re: Idle Problems
Post by Fidget on Mar 31^st, 2007, 8:14pm

on 03/31/07 at 20:04:29, scorpio_man wrote:

hi there

don't like the MAF figure, a bit high. if you send me the scan (the 3 files), i'll have a look at it for you.

hth

Thanks!

*edit - silly me, forgot each scanlog file produces 3 files, sorry. email in the pipe sir!

Many thanks.

Title: Re: Idle Problems
Post by scorpio_man on Mar 31^st, 2007, 8:25pm

hi there

if you go into car code folder from my computer, then into samples. you'll then see your scan saved as 3 files. put them into a zip file and send it to me.

i need the 3 same named files or it won't work. see http://www.fordscorpio.co.uk/obdfaq.htm

hth

Title: Re: Idle Problems
Post by Fidget on Mar 31^st, 2007, 8:30pm

on 03/31/07 at 20:25:55, scorpio_man wrote:

Yes, sorry. I ahve sent the three files but I didn't zip them up (I hope that's not going to cause you any trouble :-[ they should only be about 97kb all together).

Title: Re: Idle Problems
Post by scorpio_man on Mar 31^st, 2007, 8:43pm

hi there

i'd give the MAF another clean as it's a bit high. also check the wiring to the TP as it moves around a bit.

when you've done this, do the following scans.....

RPM
MAF
LTFT
BOTH LAMBDA SENSORS (if there's two pre cat)
run these for 5 mins at idle (a/c OFF). every minute, blip the throttle to 2k rpm. end this scan.
then do another scan, switching on and off various temp sensors. also check the tps with the engine off (ignition on). should be from 16% to 92% ish.

try not to drive it on the scan.

hth

Title: Re: Idle Problems
Post by Fidget on Mar 31^st, 2007, 8:51pm

on 03/31/07 at 20:43:48, scorpio_man wrote:

Thanks Squire, I will do that tomorrow so as not to annoy the neighbours tonight. Its a 2.0 16V so only one precat Lamda.

" ... switching on and off various temp sensors ... " - I'm not quite sure what you mean by that :-[

Title: Re: Idle Problems
Post by scorpio_man on Mar 31^st, 2007, 8:56pm

hi there

engine coolant temp and air intake temp. do this on the engine off scan with the TP, after the 5 min run. it's just to make sure they're working correctly.

cheers

Title: Re: Idle Problems
Post by Fidget on Apr 1^st, 2007, 2:32pm

Just completed the scans and sent them off.

I did notice that the TPS is still fluctuating with the engine off (16.9 to 17.3%) which kind of suggests that the wiring or sensor has a problem. Looking at the wiring, its the one sensor that I have not replaced the wiring to as yet - it is still flexible and I can't see any cracks, but the wires are bound together for some of its length. I'll get to replacing that wiring later or tomorrow I think.

Thanks again for your help Andrew.

Title: Re: Idle Problems
Post by scorpio_man on Apr 1^st, 2007, 6:41pm

hi there

email sent back.

cheers

Title: Re: Idle Problems
Post by Fidget on Apr 10^th, 2007, 10:41am

update:

Andrew, the scan was better for the IAC when running it from cold to warm (no driving).

I replaced all the cracked wiring I could find around the TPS, IACV and IAC, so its all good now, but still the problems remain...

The slightly fluctuating value (16.9 to 17.3%) of the TPS is still present, but giving it some thought (before I go shelling out on a new one) I wonder why it is that the values (Idle Speed) drop to correct values when the Air Con Compressor kicks in. I am guessing at the moment that there may be some sort of another electrical problem, but I have not yet pinpointed what other components are involved in maintaining idle speed.

The other thing I am concerned about is, whilst replacing the wiring it was necessary to remove the air intake hoses, which gave me the chance to take a further look at the throttle plates. I think they may have been disturbed at some point, there's some evidence of that around the screw heads. Then I got to thinking about the positioning of the plates themselves which are not completely closed. Now I could be wrong, but I thought on engines with engine management that the throttle plates are normally fully closed at zero throttle and the idle speed and mixture is controlled by the air bypass valve and timing. In my case there is visibly very slight opening but the screw adjuster for the throttle stop does not appear to have been disturbed. So I have been contemplating taking the stop back a touch until I get a 16% minimum reading for the TPS, but I am not rushing into that without advice first.

The other thing that is still baffling me is the slight vibration between 15 and 20 mph (which improved slightly after replacing the IACV). Switching the Traction Control on or off makes no difference and its only when the engine is warm to hot.

Anyway, being a full time Dad (I hate the expression - House Husband) to three kids I have little time to do things, but I have two days this week that I can press on with things. I think I need to find much more detailed explanations of how the fueling system functions from cold to hot on the site so I'm off to do that search now. Its so unfortunate that there is no official manual for the car, but thank god for this site.

Thanks for your help so far guys :)

Title: Re: Idle Problems
Post by Simmo on Apr 10^th, 2007, 10:57am

Does THIS page (http://www.fordscorpio.co.uk/fuelsystem.htm) help a harassed father!? :D

Title: Re: Idle Problems
Post by Spannerdemon on Apr 10^th, 2007, 11:00am

There IS a manual for the car Fidget. Plenty of people sell it on Ebay on a CD, but there is no Haynes or similar.

You should be able to pick one up quite easily. ;)

Title: Re: Idle Problems
Post by scorpio_man on Apr 10^th, 2007, 11:24am

hi there

i'm going to have a look at my car tomorrow (wife has it today) to be sure about the butterfly, but i do think it should be fully closed.

have a look at this site, (http://www.btinternet.com/~madmole/HowDoI/Howdoi.html#Modify%20the%20Throttle%20Body) it gives a good write up about cleaning the TB.

not sure about the vibration. strange. :-/ i'll have a think about it.

re the manual. all the most important parts are on the site. plus you get all of us thrown in for free! ;D

btw, have you tried running with the tp disconneted (carefull of the wiring)? see how that goes.

Title: Re: Idle Problems
Post by Spannerdemon on Apr 10^th, 2007, 12:01pm

Yes, I agree with Scorpio-Man. There is NO substitute for swopping ideas with people (US) who actually own the cars. Manuals are great, but WE are better ;D ;D

I am a huge believer in this Club and its great members. :D

Good idea to disconnect the wiring from the TPS. This was the giveaway that convinced me that mine was faulty, as with it disconnected, I suddenly had fewer problems. Might not work for everybody...but it sure did for me. They DO just fail and as it was pointed out to me, even though the readings were OK, it HAD gone faulty, and was probably 10 years old.

Since fitting the new TPS the car has been an absolute dream to drive again. ;)

Title: Re: Idle Problems
Post by Tompion on Apr 11^th, 2007, 3:41am

on 04/10/07 at 10:41:04, Fidget wrote:

update:
So I have been contemplating taking the stop back a touch until I get a 16% minimum reading for the TPS, but I am not rushing into that without advice first.

I would be very cautious about touching the stop screw.
I don’t know for certain but assume that the % value is set by the engine management regardless of the throttle position after a battery disconnect – meaning if you adjusted the screw to 16%, next time you disconnected the battery it would return to say 16.8% (which is what mine reverts to).

By the way I did a diagnostic on mine to check how the IAT reading compared, and it was much the same when up to running temperature, but something I hadn’t realised was that the desired idle speed control (RPMDSD) varies as the engine warms up – just wondered whether it might be worth checking this value when your engine has a high tick-over in case something is telling it to do this as opposed to a sticking throttle or IACV.

With coolant at 56 & IAT at 58 the desired idle speed 1184 RPM
With coolant at 198 & IAT at 92 the desired idle speed 864 RPM
2.3 engine

I also think it sounds like a faulty TPS.
Dave

Title: Re: Idle Problems
Post by Simmo on Apr 11^th, 2007, 6:37am

Unless yours is different the throttle stop screw is pre-set and crimped so that it cannot be adjusted. Essentially as has been said if there is a problem with the idle it is indicative of a problem elsewhere and the 'brain' is trying to compensate.

Title: Re: Idle Problems
Post by Spannerdemon on Apr 11^th, 2007, 8:01am

Quote:

I would be very cautious about touching the stop screw.

Don't go there. Leave it exactly as it is, safely factory set under its protective cover. This will NOT be your problem. If you mess with this, you WILL have made even more problems.

When I replaced my own TPS, I had already thoroughly cleaned the throttle body, butterfies, spindles and linkage. I then assembled with all new gaskets. You need to make sure the whole throttle body is spotless.
Use Carb Cleaner, cotton buds, etc etc but take care when cleaning the spindles as they are quite delicate.

Fitting the new TPS. You need a new gasket £9.00 from Ford or about 3p if you cut your own........ :D Even the guy at Swansons Ford in Newton Abbot. (My local Ford dealer) was horrified at the cost of this 2" gasket.

Fitting. Disconnect your battery.

Hold the gasket in place with a spot of gasket sealant. Offer up the new TPS, with the securing plate (the old one will be just fine) behind it, and slide them onto the protruding shaft.
Without turning it at all, gently bolt it into place with the two long thin bolts. That's it. Bend the tabs over to lock the nuts.

Basically if you haven't turned the throttle butterfly shaft whilst fitting it, it will be in the right position, with the valves closed. If, of course, you've messed with the stop screw, then it won't. Simple really.

This is the advice I got from the Senior Mechanic at Ford, and it was 100%. You don't need to use a meter on it to set it. The ECU will adjust itself to suit this position.

Re-connect the plug, and then re-connect the battery.

Go for a drive of about 10 miles. The ECU will now 'learn' the new TPS settings, and your car should run smoothly again without any gear clunks. Your idle will be perfect, and your fuel consumption will improve.

That's how it should go anyway. ;)

Title: Re: Idle Problems
Post by Fidget on Apr 11^th, 2007, 10:19am

Many thanks for the helpful replies gents!

Simmo - that page didn't help, but this one - http://www.fordscorpio.co.uk/pooridle.htm - was more informative regarding what the ECU uses to determine idle speed.

Spannerdaemon - I've got one of those manuals and it seems to be exactly the same as the information this site provides. I was hoping to find something on this engine in something like the Haynes Engine Management Manual, but this model is not covered. However, the page mentioned above gave me an indication of what sensors are used by the ECU to determine engine speed.

RE: the forums, I fully agree, I've found these forums to be clean, respectable and full of friendly and invaluable help and advice. And that really is better than any manual. Just after I made my last post and before your replies, I had already made my first donation, I think its well worth it.

RE: the throttle stop, I agree, its best left alone, I was just concerned that the plates are not in the fully closed position. I had already cleaned them and the throttle body to clean metal using carb cleaner and a toothbrush and cotton cloth then blasted it all off with an air duster. There was a lot of carbon, that made me think at first that the lack of it could contribute to the racing idle but I don't think it should really be the case. I cleaned it up because of a lumpy idle and thumpy gears (although they are no where near as thumpy as when I disconnected the TPS).

Yesterday I managed to snatch a few minutes to disconnect the TPS and the result was a bit horrifying :) - incredibly thumpy gears, so much so that on changing up from 1st to 2nd produced a brief screech from the back wheels. The idle was the same also, so that did not produce any positive result.

I also looked again at the throttle plates and took the hasty decision of loosening the screws slightly to see if they had been so badly misplaced as to stop the them closing properly, the screw holes in the plate must be over sized since they moved freely. I centred them and re tightened the screws (idle exactly the same).

So, following my study of http://www.fordscorpio.co.uk/pooridle.htm, I've made myself up a list of things to look at - i.e. IAT, ECT, TPS, MAF, CKP. I'll take another scan on Thursday and graph them, but looking at previous scans ...

The IAT is okay I believe, readings steadily rise as the voltages steadily drop.

The ECT is also okay I believe, same thing - temperature steadily rises and voltage drops correspondingly.

The TPS is as before, fluctuating between 16.9 and 17.3%, but reconnecting it after disconnecting it restored a smoother gear change (although still a bit thumpy). Perhaps it is developing a fault, but it doesn't explain the racing idle even if it is developing a fault.

The MAF also appears to be okay, as I said in a previous post, the readings look good compared tow hat I have found on the site.

The CKP made me realise that I hadn't checked the wiring to that. So that is a job for Thursday, but I looked through each of my scans and found that it had been consistently reading 0.000 at standstill.

Looking at what the ECU uses to control idle (IACV, Spark Advance and Fuel Pulse Width)...

I checked the IACV readings also, and they are a consistent 19.922 at warm idle (its new as well).

The Spark Advance fluctuates between 7.5 and 9.3, although i noticed on one reading that it jumped up to 13.5 for a very brief moment. I cannot find any guidance on what the spark advance should be for this engine though :( I did replace one of the coil packs a few months ago, maybe I should replace the other one, but other than I replaced the plugs and leads at the same time.

Fuel Pulse Width also fluctuates a bit - between 532 and 580 (although it dropped to 484 when the spark advanced jumped to 13.5). Again, I cannot find any guidance on what the expected value should be.

I think that if the readings are as expected then it must be umetered air via a leak in the induction system somewhere. Having been around what connections I can find in the engine bay with a hose stuck in my ear, I haven't heard any significant hiss, but its so tight around the plenum chamber and throttle body. I'm still looking for my leak detector spray to check for any bubbling but still can't locate the can yet. I've been checking for vacuum in the fuel tank, and its always there when I stop at the petrol pump although it dies off after a few hours. I think I'm going to go round the vacuum hoses with my hose clamps on Thursday morning to see what happens.

I think its best to get the idle speed to a correct value (btw the RPMDSD is 864 with IAT at 78 and ECT at 198 ), i.e. not racing at over 1000rpm first before ironing out a lumpy idle. Hopefully it would cure both.

Seriously, I cannot thank you all enough for your help and guidance :)

.

Title: Re: Idle Problems
Post by Fidget on Apr 22^nd, 2007, 8:50pm

I'm a bit late in bringing an update to this ..

A few days after my last post, the car passed the MOT first time despite the idle problems :)

Anyway, I finally got a few hours to go through everything last week and found nothing wrong with any of the sensors. However, having read through the TPS data at http://www.fordscorpio.co.uk/tpsdata.htm and having found that at closed throttle the TPS was returning a resistance of 764 ohms (rather than the 700 ohms that it should be), I began to wonder again if the throttle stop was indeed the issue. I checked to see if I could adjust the reading by rotating the TPS with the fixing bolts loosened, but the reading just went higher.

I got to work with a toothbrush and some carb cleaner, brought the throttle stop and screw to bright metal (thinking that maybe there was a layer of dirt between the two). I found no change after the cleaning, but on very close inspection there seemed to be score marks on the inside of the right angle of the throttle stop. Considering the problems here only occured after I had thoroughly cleaned the heavily gummed up throttle plates and housing, I thought that this culd be a sign that at some time someone may have seen fit to adjust the throttle stop to correct a poor engine idle rather than clean the throttle and plates as I had.

Anyway, having also read http://fordfuelinjection.com/index.php?p=30 I found that if the throttle stop had been adjusted, the TPS should also have been adjusted to give the proper reading at closed throttle, or else the ECU could think that the engine had not reached idle at all.

So, with the knowledge that I could return any adjustment to the thottle stop to the exact place (because I had a meter reading from the TPS as a reference point), I took the executive decision to move it out so that I could achieve the 700 ohm value that the TPS should be giving. Once done, I rechecked the throttle plates to make sure that they were not sticking (i.e. misaligned on the spindles, because as I said before, the screws showed signs of tampering).

Quite a while later, I fired her up and hey presto - no more racing idle, no more hanging throttle and no more engine vibration. In fact I now had a smooth idle at 864rpm, smoother gear changes and no fluctuations with the aircon on or off.

I belive I have finally solved this one, and not without the help of the forum. Once again, many thanks guys.

Title: Re: Idle Problems
Post by scorpio_man on Apr 22^nd, 2007, 9:09pm

well done! that was some investigating. :)

Title: Re: Idle Problems
Post by petehull on Apr 22^nd, 2007, 9:12pm

[]
It reads like a Sherlock Holmes novel....Congrats in order... ;D

Pete

Title: Re: Idle Problems
Post by Simmo on Apr 23^rd, 2007, 6:25am

Well done Fidget... ;)

Title: Re: Idle Problems
Post by Spannerdemon on Apr 28^th, 2007, 12:34pm

Well done indeed. I like people who don't give up on problems.

As I found, somebody who'd had the car before me had messed with the Throttle stop screw, and I had major problems getting it all set up properly again.

Top Man!! :)