98 V70AWD Missing on 4,5,random - replaced plugs,,wires,cap,

Andrew Vanis · Post by **Andrew Vanis** » 25 Mar 2015, 17:24

1998 V70 AWD so it has the 2.4 turbo.

Misses under light load, typically on deceleration. Typically going form 1,500 rpm down. Sometimes stumbles on acceleration. Sometimes dies at the light. Idles fine upon start up. If stumbles, I can keep it going by accelerating.

Replaced plugs (NGK copper to .28), wires, cap and rotor.

Ideas?

draser · Post by **draser** » 26 Mar 2015, 20:29

Codes?

Post by **rspi** » 26 Mar 2015, 20:57

Andrew Vanis · Post by **Andrew Vanis** » 26 Mar 2015, 21:20

300 = random/multiple
304 = cyl 4
305 = cyl 5

Post by **erikv11** » 26 Mar 2015, 21:55

Try cleaning the Idle Air Control valve.

Other possibilities that come to mind: throttle position sensor going bad (difficult to troubleshoot), MAF going bad (but usually gives a code, easy to test by unplugging it), fuel supply (furl pump relay, less likely fuel pump).

Post by **shaker_chi** » 27 Mar 2015, 13:53

Hate to say this, but these cars are very picky when it comes to plugs. I would try a set of O/E Volvo plugs. Also, what brand wire set did you put in? Was it 7mm or 8mm? Before you go spending more money though, I would do a thorough check of the wires to make sure you have a good connections.

Post by **erikv11** » 27 Mar 2015, 20:22

Very picky about plugs yes, but NGK coppers are known to be a good choice.

draser · Post by **draser** » 27 Mar 2015, 21:15

If misfire is consistent on those 2, did old plugs look different than other 3? Maybe whiter or more fouled? Are you loosing any coolant?

Andrew Vanis · Post by **Andrew Vanis** » 09 May 2015, 06:11

after exhaustive diagnostic, the ECU appears to be bad. Was told to look for a replacement. Have a separate post on that here - https://www.matthewsvolvosite.com/forums ... =1&t=69789

wondering what other years / models I can pull one from.

Post by **cn90** » 09 May 2015, 07:44

As mentioned above.

Plug: NGK or Bosch
Cap/Rotor: Bosch only!
Ignition Wires: Bougicord only! Make sure they are installed in the correct order!