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Discussion Starter · #1 ·
First time posting here but long time follower, reading other people’s issues has helped me immensely. Hoping the group can provide some insight on my own set of bizarre issues this time. Here’s the full rundown:

2007 Volvo S40 2.4i automatic with 103,000 miles. Haven’t had any major issues aside from the dreaded sunroof leak (which forum help and $2 of tubing saved me from a $500 dealer bill) and a couple of sway bar replacements.

Initially started when I noticed a couple of thumps shortly pulling away from my street parking spot. The car drove normally after that on a short trip to pick up dinner. Early the next morning the car started normally again then right once I drove away the engine cut out and I was unable to restart the car. The engine would only sputter and was unable to fire. I was forced to have the car towed to my local mechanic.

The shop spent 2 hours trying to diagnose the issue - ultimately they discovered that the sound I heard was a rat that had been hiding out under my hood. The mechanic showed me a picture of the dead rat in the engine compartment - and a few bits and pieces on some of the components. They deduced that somehow the rat had gotten itself into a spot where it caused the timing belt to jump - they said it was off 6 teeth. They said they inspected the surrounding hoses and wires and did not notice any other damage, nor any valve damage caused by the jumped timing. I gave them the go-ahead to do the full timing belt replacement (including water pump) at a hefty price tag, figuring that it should be done around this time anyway.

Well, I picked up the car last week and drove it home about a mile and it seemed fine. On the weekend I drove it further to get an emissions test - about 3 miles in I was forced to stop quickly at a red light and the engine cut out. I was able to turn the car off and get it restarted, the “reduced engine performance” and “engine service required” notifications popped up and it went into limp mode. A few miles further, the engine started jerking and sputtering and wouldn’t go over 15mph; I was forced to pull into a parking lot and call for a tow.

I brought it back to the shop that replaced the timing belt - they drove it twice for about 20 minutes but were unable to recreate the issue. They pulled a p0121 code and Volvo codes 914c (Electronic Throttle Module), 9918 (Throttle Unit), and 950c (Accelerator Pedal Pos Sensor). They suggested I replace the ETM and quoted $600 for the part. I’ve been reading up on the wealth of ETM and MAF knowledge here, but I’m skeptical that this is the issue (or the only issue). Seems like quite a coincidence that the part would fail at the same time that a rat was found under the hood. I’m worried that there could be some wiring or hoses that my rodent friend started gnawing on before he expired that could be causing some issues.

I’m considering taking it into a Volvo dealer for an ETM sweep to try to determine if that’s ultimately the issue. Does anyone have any other suggestions for trying to isolate the problem or directions to point the dealer in when asking them to run some diagnostics?

Thanks,
Brian
 

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When you put the key in and turn to POS 2, if you listen to where the throttle body is can you hear a really weird, almost modem machine like sound? If so, it is doing its self test sweep.


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I would check your connections and wires, pulled this from another site: https://www.matthewsvolvosite.com/forums/viewtopic.php?t=81801

2008 S40 ECM-91AC, ECM-9918 CODES
Post by dreadie » Fri Jun 30, 2017 6:34 pm

Long time lurker, first time poster. My 2008 S40 has been plagued recently with multiple ECM Codes via vida:

ECM-91AC - Throttle Valve - Faulty Signal
ECM-9918 - Throttle Valve - Faulty Signal
ECM-9A0A - Vehicle Beaviour - Behaviour 4

(This also leads to reduced engine performance)

This started to occur about 2 months ago, at which point I replaced (with a used) the throttle control valve/module assembly and cleared the codes - this "fixed" the problem for two months, however it reared its ugly head again on me today.

I got another throttle control valve/module and replaced it again, cleared the codes like before, however now the codes are coming back w/ reduced engine performance. Only difference is this time since it was replaced, under acceleration there is a ticking noise coming from under the hood/bonnet, almost like a clock ticking.

Anyone have any thoughts on where to go from here? Thanks in advance.

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Post by dreadie » Mon Jul 03, 2017 1:55 pm

Got it figured out - separated wire at the throttle module connector - broke about .5" away from the plug, temporarily resoldered, new plug on the way.

Thanks for the assistance.
 

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Something like this sounds like a 'coil pack' issue to me. Before you give the green-light for more expensive repairs I'd look into them first. They are relatively inexpensive if you opt for OEM/aftermarket parts and can be worked on by yourself. Who knows, it might just fix your problem.
 

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Discussion Starter · #5 ·
Thanks, everyone. I appreciate the responses. Took it to my local dealership - I guess the good and bad news is that they weren't able to find anything. Unfortunately the codes were cleared so they were unable to get a more detailed diagnosis. But, they said the throttle was performing fine and there was no damage to the wiring. Hoping it was just a fluke, but I'll keep those ideas in mind the next time it acts up.
 
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