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Topic: Verdict on DTCs (Read 928 times) |
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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Verdict on DTCs
« on: Mar 27th, 2004, 11:06am » |
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Right, finally got to talk to the PCM in my new 24v and I have stored codes
P0113 - Intake air temp high input
P0131 - O2 Low voltage B1 S1
P0138 - O2 High voltage B1 S2
P1152 - Lack of H02S21 switch - Indicates rich
Currently the car mpg is low 20's and varies, seems to lack power and had suffered from a misfire caused by EGR and Jet Washing wetting the plugs.
From the above I'd guess a new air temp sensor is in order plus it looks like a new set of HO2 sensors?
Can anybody confirm if H02S21 is a fueling sensor and is it possible to swap pre/post cat sensors as an interim move?
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1996 Mk4 2.9 24v Estate
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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Re: Verdict on DTCs
« Reply #3 on: Mar 28th, 2004, 3:09pm » |
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Thanks Eric, most useful.
I changed the IAT and P0113 has gone. So now left with
P0151 - H02S21 Out of range Low volts, Bank 2
P0155 - H02S21 Heater Malfunction, Bank 2
P1131 - Lack of switching, Bank 1
Did have a P1151, Lack of switching Bank 2, but I presume that code has been promoted to 151/155. I'm using an ELM320 based reader which I believe is incompatible with VE but works well with a Palm 3.
I've checked and cleaned all the HO2S connections so next I think it's two new pre cat sensors. At least I invested in a reader rather than just replacing the sensors.
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1996 Mk4 2.9 24v Estate
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Eric_R
Administrator
Cosworth Owner 1998 - 2006 & site co-founder
Posts: 1792
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Re: Verdict on DTCs
« Reply #4 on: Mar 28th, 2004, 4:25pm » |
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Tony,
I've heard of the Palm Pilot programs but not seen one working. As well as DTCs, can you log the data coming from the sensors, or perhaps it has an HO2S screen, like VE?
HO2S sensors use similar technoology to Catalysts and suffer from much the same problems - oil contamination, overheating caused by misfire, all those things - so they do fail. Sometimes it can be other problems rather than the sensor itself. With datalogging on VE we can actually watch the sensors and see how they perform, but in your case I think you had a serious misfire and cooked a catalyst? In this case I would bet they need changing because they've probably been fried.
Nice to see someone using the new technology - can you get us any screen shots or photos of the Pilot working? Id like to see it.
EricR
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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Re: Verdict on DTCs
« Reply #5 on: Mar 28th, 2004, 5:26pm » |
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Yup, I potentially fried my CATs in Coventry. Water in the plugs from a jet wash, leading to a misfire, leading to fuel in the CATs.
Strange thing is the misfire was Bank 1, the DTCs are mainly reporting Bank 2 HO2S failing. I'm guessing both sensors are well due for replacement and as www.cats-direct.com have them for £30+VAT each it's not too much pain to replace them.
(added - using the sensor data Bank 2 precat is max 100mv most of the time but does jump to 1.25v, whilst postcat is reading 1.25v and the fueling is closed under Failure Effects Management, most clearly showing it's likely to be the sensor and not the wiring).
I did get to the EGR gas nuts using the long socket extension and crows feet sockets brought especially for the job but on reconnecting the EGR vacuum the 2000 rpm misfire reappeared - I'd say without proper closed loop fueling the PCM is unable to maintain smooth running at the extreme lean.
The Palm software only seems to be able do read and decode DTC's with my Palm III, the logging feature does not appear to work. Once I've got the fueling sorted I'll have more time (and money given the current mpg) to experiment more and take some photo's. It's alot easier to work with an old Palm rather than my employers expensive laptop!
I'd recommend everybody thinking of buying one of these cars who has a PDA to get a OBD2 PWM cable and plug in on the forecourt. For under £100 you could save yourself a small fortune or stand a better chance of negociating a better price. I got mine in the end from http://gendan.co.uk/auto/index.shtml who rent and sell a range of OBD2 diagnostics kit including the ELM32x based DIY units.
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Eric_R
Administrator
Cosworth Owner 1998 - 2006 & site co-founder
Posts: 1792
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Re: Verdict on DTCs
« Reply #6 on: Mar 29th, 2004, 7:22pm » |
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Excellent, Tony. If you could do a page for us we'd love to see it. I'll stick with VE myself - the datalogging function is hugely useful and essential for understanding some sensor problems but if you have a Pilot what a gadget.
Re the part-throttle misfire - yes, once the seal on the EGR orifice pipe is broken it has proved to be a problem to reseal it and part-throttle hesitation is very common - caused by the mixture, already very leaned off under closed-loop, being too weakened by an air leak through the EGR pipe.
BTW, P0131 and P0138 refer to the Bank 1 sensors, which is the driver's side of the engine, P1152 the passenger side. I'd bet that once the HO2S sensors are working properly you'll get the faulty catalyst DTC next.
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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Re: Verdict on DTCs
« Reply #7 on: Apr 2nd, 2004, 8:58am » |
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.. the story continues.
Ordered two new HO2S from www.cats-direct.com, arrived next day totalling under £80 inc delivery. Went to fit them and found that on the 24v you need a 22mm cut out deep socket (which cats direct had for £5 but I decided not to order!)
So pending the work until the weekend I reconnected the sensors and found that the Bank 2 connector was definately not fitting properly so spent some time cleaning and making sure the connector snapped tight.
I'd also disconnected the battery so setting off for Coventry was expecting a tough time as the PCM remapped and relearnt it needed to enter FMEM. After 150 miles of near perfect performance and economy I checked the DTCs - NONE!
After driving to/from the hotel I did then get a P131 (Bk 1 Low Volts). As I have replacement sensors it makes sense to replace the fueling HO2S's anyway - I've got the average mpg up to just over 25mpg (from 22) on the high speed sprint along the M40, M25.M23. Cruise locked 70mph on level road (A46) showed average of 35mpg over about 5 miles!
Of course all this mucking about has left me with a stall problem and I'd guess the coolant fans/temperature switch are not working but that's another story.
Quick edit to say :-
Fitted Bank 1 pre cat ok, rounded off Bank 2 pre cat so now need to wait till next weekend to either brute out or strip back the exhaust manufold after sourcing the necessary nuts and gaskets.
Luckily it was Bk1 causing problems so DTC's all gone (for now) and switching looks ok if not perfect. Having got hold of some alternative ELM320 software I now have logging to a PC so next journey (which is to Southport) I'll take a complete log to see what the post cat HO2S's are doing.
Tried reconnecting the EGR but still the misfire so still more work left to do there. I've ordered 4 new O rings (2 spares if I have to strip down again) for the bank 2 induction manufold and further checks for airleaks to follow.
I'll try to write the whole story up during the next weeks as it might help other people moving to the Mk4 24v.. I get the distinct feeling that any future cars for sale are likely to suffer the same 'get rid of that money pit' feeling mine probably gave the last owner. From working on the engine it's clear somebody else has been there before me.
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1996 Mk4 2.9 24v Estate
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