1999 s80 misfire no throttle response

kosh_al · Post by **kosh_al** » 10 Aug 2014, 06:16

My car (1999 S80 2.9L non-turbo) has been acting up intermittently for about a year and it finally died. To begin with it intermittently would "sputter" or misfire at interstate speeds like just when I get on the throttle hard to pass someone at 80mph or so. It felt like it was misfiring for a mile or two and if I stayed off the throttle it would clear up and drive fine. I read the codes and there was P0036, 0136, and 1330. The 1330 is CVVT solenoid and this has been in the system for about two years but the car drives fine. I had a mechanic replace the passenger side rear o2 sensor and he said if the code comes back, I probably need a catalytic converter? The code came right back but I drove it anyway and the car still would do the sputter/misfire thing at interstate passing speeds.

About two weeks ago I crank the car and it was misfiring VERY badly and I could not rev past 1700rpm. I read the codes and there were probably about 7 or 8 codes in there all to do with the rear o2 sensors on both sides. I didn't record the codes because I cleared the codes and wanted to see what came back. No codes came back except the 1330 but still the throttle wouldn't go past 1700rpm and the misfire would clear up intermittently. The only code I believe I remember seeing was the same P0036, 0136, and 0054. Now most of the time the engine runs smooth except no throttle response. I thought maybe the catalytic converter is clogged so I unbolted the exhaust at the manifold but still got no throttle response. I cannot drive the car anywhere and I know the local volvo mechanics will charge an arm and a leg for repairs and the car is maybe worth $2500, so... I don't know what else I can check. The car now will only rev to 1300rpm and it intermittently misfires bad. The odbii code reader doesn't pick up any misfire or any codes besides 1330. I tried disconnecting the battery for a couple of days to reset to computer but no help.

Any ideas?? I just got new struts on the front and new tires and rims and I like the car and would love to fix it reasonably.

kosh_al · Post by **kosh_al** » 10 Aug 2014, 06:35

I also want to say that these forums are great! I recently replaced my A/C blower motor and resistor using instructions provided here are fixed my dead/intermittent blower for less than $100!! Awesome! Thanks guys!

matt5112 · Post by **matt5112** » 10 Aug 2014, 08:12

Well you seem to have a plethora of O2 sensor codes.

Have you inspected the wiring harnesses for the O2 sensors? Check for breaks and wires burning through.

Also try measuring voltage or checking for continuity while moving the harness to check for partial breaks.

After that, it may be the ECU that has internal faults.

How old are your spark plugs and ignition coils? Those might be failing if you're misfiring under load. However it could still be related to O2 sensors and thus fueling.

Post by **Oly_850** » 10 Aug 2014, 08:33

Misfires under heavy load are difficult to diagnose unless your engine idles and warms up without error. From dead cold (open loop, before ECU starts reading O2 sensors) how does it run? It the idle degrades once the car warms up, I would do what Matt suggests, check all of your O2 sensors for function. Misfit I g at speed is also likely to be plugs (get exactly the right kind / spec) or a weak ignition coil pack ( or a few). Let me know what you find?

kosh_al · Post by **kosh_al** » 11 Aug 2014, 14:17

I have probably 75,000 miles on the plugs (NGK) so I will change those. Not sure how to diagnose an intermittent coil pack but I have suspected that as well. Before the current problem, the car starts and warms up and drives perfectly smooth and would only misfire at speed and only sometimes.

Any ideas on the throttle?....doesn't matter if I push it to the floor it wont do over 1300rpm....I don't see any indication the car is in limp mode or safe mode.

Post by **Oly_850** » 11 Aug 2014, 19:22

If it starts and idles from cold, but won't rev much beyond idle I'd check three things:

Unplug the MAF sensor, does it run better?

Any shot you have a vacuum leak downstream in / around the intake? Hose it down ( carefully please ) with carb cleaner and see if the engine idle increases when you hit a certain spot around the intake, injectors, vacuum lines etc.

Lastly remove and clean the electronic throttle module, make sure to get the throttle plate top, bottom and body really well with carb cleaner and a nylon brush.

Let us know what you find?

kosh_al · Post by **kosh_al** » 16 Aug 2014, 15:59

I am going to get some NGK Iridium plugs and an air filter and some carb cleaner today and do a little work. I was looking on rockauto.com at parts prices and I think I can replace all of the coils for the price of paying the shop to replace just one!! (car has 191000 miles and I have only ever had one of the coils replaced) Thing is...there are quite a few coils listed on rockauto and I am not sure which would be optimal? Any opinions? Anyone used rockauto.com for parts before? Dude at work recommended them and they are definitely cheaper than anywhere else I have looked.

matt5112 · Post by **matt5112** » 16 Aug 2014, 17:10

Bosch would be ideal.

kosh_al · Post by **kosh_al** » 17 Aug 2014, 12:01

I tried the carb cleaner thing and it doesn't affect the idle. Unplugging the MAF causes the car to immediately die. I haven't cleaned the ETM yet but it is very nasty on the bottom side of it. It is still misfiring and I haven't changed the plugs yet as I think if I will change the coils, then I will do it all at once so I don't pull the coils twice.

matt5112 · Post by **matt5112** » 17 Aug 2014, 13:50

I've had all sorts of vacuum leaks and none of them would respond to brake clean. Honestly the only solution is to apply pressure to the system and listen for leaks and/or apply soapy water.

The MAF test requires the car be off, then unplug the MAF, and start it up again. If it runs better, then the MAF is likely your issue. That or there is a leak between the MAF and ETM.

There is also the VIDA ETM test which commands every position of throttle opening, and charts the reported throttle position. If that test fails, you need a new ETM as well. Is yours a white label or yellow label? Yellow label might be fine, but the white label version is almost certainly toast.