help with S70 please

tractorman5720 · Sep 23rd, 2011, 23:03

Some background info for starters - 1998 S70 2.5 20v SE, cut out in a queue on tuesday morning and refused to start again. AA was called and diagnosed that the cat had packed up and needed replacing. Got it towed home and ordered new cat. Luckily for my fiancée I pay the AA a small fortune each month but also unlucky as she has had to drive a somewhat hideous vauxhall for last 3 days( even being free doesn't make it nicer!).

Now for the frustrating bit - fitted new cat and the car still won't stay running. Will fire reluctantly but dies as soon as you take foot off. Checked plugs on off chance and found them to be very coked up. Changed these and still no change. Haynes manual keeps bouncing me from chapter to chapter and not telling me anything definitive.

Can anyone help me solve this as we liked the car up until this evening and would like to do so again.

deathrider311271 · Sep 23rd, 2011, 23:15

first question is how did the AA diagnos the cat as being faulty?
Secondly its best to get the codes read with Volvo software, it will save a lot of time and guesswork and probably money too lol.

Make sure you get the codes and post them here there are a lot of clever people here who will help with the diagnosis.

Oh and welcome to the forum

cheers

Simon

david philips · Sep 23rd, 2011, 23:21

hi i dont know how the aa diagnosed the fault with out drilling and pressure testing the exhaust but he may be onto something,sotty plugs are a sign of an over rich mixture and this could cause the cat to fail,maybe theres a blockage along the exhaust if you fitted the new cat yourself could you temporally disconnect the exhaust from the back of the cat and try starting the engine for a minute see if it runs ok if very noisy,if it does then you will have a blockage in the exhaust to deal with along with getting the rich running sorted out,good luck.

tractorman5720 · Sep 24th, 2011, 10:55

Thanks for the help so far. To answer a couple of questions - AA man diagnosed cat issue by holding hand over tailpipe and feeling little or no pressure. Cat appeared to be original and car has done near enough 170k miles so seemed plausible. Maybe its the back box that is u/s. I've been banned from touching it until a professional looks at it and have got a mobile guy with the diagnostics stuff coming first thing monday, so should have some fault codes from him. Better not be pricy as we're going on hols week monday!

deathrider311271 · Sep 24th, 2011, 11:20

Quote:

Originally Posted by tractorman5720

Thanks for the help so far. To answer a couple of questions - AA man diagnosed cat issue by holding hand over tailpipe and feeling little or no pressure. Cat appeared to be original and car has done near enough 170k miles so seemed plausible. Maybe its the back box that is u/s. I've been banned from touching it until a professional looks at it and have got a mobile guy with the diagnostics stuff coming first thing monday, so should have some fault codes from him. Better not be pricy as we're going on hols week monday!

Unless this mobile mechanic has the proper Volvo sofware to read your codes u will be waisting your money, on the other hand if he going to read your codes for free or not charge when he only manages to get a generic code thats fine

acshortt5 · Sep 24th, 2011, 11:23

The plugs will always "look" like they are running rich if you pull them out after trying to start the car.

Did the AA man actually give you the fault codes? Any OBD2 scanner can pull the engine codes from your car.

My thoughts would be - if the cat went then you would be getting fuel trim codes as the rear lambda sensor would be picking up the after effects. I would also expect a bad egg smell from a failed cat.

I would think it far more likely that it is a sensor that is CAUSING the fault. The cat may well have failed but they usually fail as a consequence of another fault.

I would buy/borrow/beg/steal an obd2 code reader to see the fault codes myself.

A quick way to rule out the MAF sensor would be to (while the engine is off) unplug the electrical connector and then start the engine. If it improves things from what they currently are then the MAF is at fault (but there could be other problems as well).

Other sensors are usually picked up on the fault codes (but not always).

The cam and crank sensors can fail causing poor running/non starting issues but not throw fault codes.

Toplights · Sep 24th, 2011, 19:01

Would the cat failing stop the car running? unless it was blocked.Have you checked any of the basics,spark,fuel.?
Sorry didn't read Andrews acshortt5 post first he may well be right.

tyrefitter · Sep 24th, 2011, 22:12

check that the silencer box baffles haven;t collapsed and are blocking the exhaust dis-connect exhaust after the cat and run car if it runs it could well be the box. I have come across this from time to time whilst working as a tyre/exhaust fitter and it does give similar symtoms to what you describe.
Trev.

NI_Volvo_Nut · Sep 25th, 2011, 08:55

Sounds like the AA guy is a gimp!

There will be little to no pressure if the damn thing isn't running, my guess will be a fuel issue, check the fuel pump relay or check for power at the fuel pump

Then usual checks, spark, fuel compression....

tractorman5720 · Sep 25th, 2011, 14:23

Been back under the beast just now, undid the clamp at the back of the cat and it started. Ran for about 2 mins then cut out. Now reluctant to start again. Just have to wait and see what transpires in the morning.

Sep 23rd, 2011, 23:03	#1
tractorman5720 Junior Member Last Online: May 20th, 2013 13:02 Join Date: Jan 2011 Location: Byfleet	help with S70 please Some background info for starters - 1998 S70 2.5 20v SE, cut out in a queue on tuesday morning and refused to start again. AA was called and diagnosed that the cat had packed up and needed replacing. Got it towed home and ordered new cat. Luckily for my fiancée I pay the AA a small fortune each month but also unlucky as she has had to drive a somewhat hideous vauxhall for last 3 days( even being free doesn't make it nicer!). Now for the frustrating bit - fitted new cat and the car still won't stay running. Will fire reluctantly but dies as soon as you take foot off. Checked plugs on off chance and found them to be very coked up. Changed these and still no change. Haynes manual keeps bouncing me from chapter to chapter and not telling me anything definitive. Can anyone help me solve this as we liked the car up until this evening and would like to do so again.

Sep 23rd, 2011, 23:21	#3
david philips panic captain manwaring ? Last Online: Jul 2nd, 2018 17:16 Join Date: Aug 2011 Location: craggy island	cat hi i dont know how the aa diagnosed the fault with out drilling and pressure testing the exhaust but he may be onto something,sotty plugs are a sign of an over rich mixture and this could cause the cat to fail,maybe theres a blockage along the exhaust if you fitted the new cat yourself could you temporally disconnect the exhaust from the back of the cat and try starting the engine for a minute see if it runs ok if very noisy,if it does then you will have a blockage in the exhaust to deal with along with getting the rich running sorted out,good luck.

Sep 24th, 2011, 11:23	#6
acshortt5 Volvo Nutcase Last Online: Jul 14th, 2023 12:57 Join Date: May 2007 Location: N/A View Photos By: acshortt5	The plugs will always "look" like they are running rich if you pull them out after trying to start the car. Did the AA man actually give you the fault codes? Any OBD2 scanner can pull the engine codes from your car. My thoughts would be - if the cat went then you would be getting fuel trim codes as the rear lambda sensor would be picking up the after effects. I would also expect a bad egg smell from a failed cat. I would think it far more likely that it is a sensor that is CAUSING the fault. The cat may well have failed but they usually fail as a consequence of another fault. I would buy/borrow/beg/steal an obd2 code reader to see the fault codes myself. A quick way to rule out the MAF sensor would be to (while the engine is off) unplug the electrical connector and then start the engine. If it improves things from what they currently are then the MAF is at fault (but there could be other problems as well). Other sensors are usually picked up on the fault codes (but not always). The cam and crank sensors can fail causing poor running/non starting issues but not throw fault codes. __________________ Andrew 1998 S70 T5 CD AUTO Previously a 1990 240 GLT-R Last edited by acshortt5; Sep 24th, 2011 at 11:25.

Sep 24th, 2011, 19:01	#7
Toplights VOC Member 23660 Last Online: Apr 25th, 2024 23:18 Join Date: Apr 2007 Location: Surrey View Photos By: Toplights	Would the cat failing stop the car running? unless it was blocked.Have you checked any of the basics,spark,fuel.? Sorry didn't read Andrews acshortt5 post first he may well be right. __________________ Old Works Motor. Malcolm and my Wheels, 1998 V70 2.5 20 Valve Auto Classic,Unmodified. Last edited by Toplights; Sep 24th, 2011 at 19:04.

Sep 24th, 2011, 22:12	#8
tyrefitter Junior Member Last Online: Nov 23rd, 2012 17:53 Join Date: May 2011 Location: cheadle	s70 check that the silencer box baffles haven;t collapsed and are blocking the exhaust dis-connect exhaust after the cat and run car if it runs it could well be the box. I have come across this from time to time whilst working as a tyre/exhaust fitter and it does give similar symtoms to what you describe. Trev. __________________ Previous volvos 340 dl 1.4, 340gl 1.7x2 340 1.7 gl se 240 glt ,740 gle saloon ,740 16v saloon ,440 gle 1.7 v40 1.8. Present volvos 850 2.0 20v se est,850 2.5 10v saloon. Last edited by tyrefitter; Sep 24th, 2011 at 22:24.

Sep 23rd, 2011, 23:15	#2
deathrider311271 I've Been Banned Last Online: Jun 21st, 2022 19:26 Join Date: Mar 2010 Location: Grimsby	first question is how did the AA diagnos the cat as being faulty? Secondly its best to get the codes read with Volvo software, it will save a lot of time and guesswork and probably money too lol. Make sure you get the codes and post them here there are a lot of clever people here who will help with the diagnosis. Oh and welcome to the forum cheers Simon

Sep 24th, 2011, 10:55	#4
tractorman5720 Junior Member Last Online: May 20th, 2013 13:02 Join Date: Jan 2011 Location: Byfleet	Thanks for the help so far. To answer a couple of questions - AA man diagnosed cat issue by holding hand over tailpipe and feeling little or no pressure. Cat appeared to be original and car has done near enough 170k miles so seemed plausible. Maybe its the back box that is u/s. I've been banned from touching it until a professional looks at it and have got a mobile guy with the diagnostics stuff coming first thing monday, so should have some fault codes from him. Better not be pricy as we're going on hols week monday!

Sep 25th, 2011, 08:55	#9
NI_Volvo_Nut Volvologist Last Online: Dec 6th, 2023 11:13 Join Date: Aug 2008 Location: Bangor - Norn Iron View Photos By: NI_Volvo_Nut	Sounds like the AA guy is a gimp! There will be little to no pressure if the damn thing isn't running, my guess will be a fuel issue, check the fuel pump relay or check for power at the fuel pump Then usual checks, spark, fuel compression.... __________________ What's the matter with the car I'm driving? Can't you tell that it's out of style? Should I get a set of white wall tires? Are you gonna cruise the miracle mile?

Sep 25th, 2011, 14:23	#10
tractorman5720 Junior Member Last Online: May 20th, 2013 13:02 Join Date: Jan 2011 Location: Byfleet	Been back under the beast just now, undid the clamp at the back of the cat and it started. Ran for about 2 mins then cut out. Now reluctant to start again. Just have to wait and see what transpires in the morning.

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