inetadv Posted August 4, 2015 Report Share Posted August 4, 2015 Hello,I have a '99 S70 AWD that is giving me fits. I have the timing marks all dialed in on a belt replacement. The car starts - with difficulty. I need to pepper the throttle to keep it running until it gets warm enough to maintain rough idle. At that point I can apply the accelerator and get an rpm response (although somewhat sluggish on the response.) BUT if I apply the brake pedal, the engine drops back to idle and becomes completely unresponsive to accelerator. Lift off the brakes and throttle resumes responding. Touch the brakes again and pushing the accelerator even to the floor does nothing. The ETS light is also on. I've seen some posts regarding a similar condition, but the answers went off topic. I would like to know what is the mechanism by which the brakes and throttle are intertwined, such that touching one nullifies the other. What parts or sensors tie the separate systems together and could cause this response where the throttle cuts out? Many thanks for any help as I'm at my wits end.Joe Link to comment Share on other sites More sharing options...
Fran9690 Posted August 4, 2015 Report Share Posted August 4, 2015 This all happened after your T-belt replacement? Did you correctly orient the vvt hub during replacement? The cam might have shifted in the head and the hub stayed in the same spot, which will make your actual timing off, causing driveability issues. You said the ETS light is on, have you checked codes? Link to comment Share on other sites More sharing options...
inetadv Posted August 6, 2015 Author Report Share Posted August 6, 2015 Thanks for the response, Fran.I oriented the back end of both cams with the slots flat horizontally matching up with the seam of the top cover and main head. I tried setting the timing belt two ways - because I couldn't find definitive directions on which was right. First I tried putting the belt on the exhaust cam with the exhaust VVT hub left unsprung - ie. not pre-loaded clockwise relative to its cam. I also tried putting the belt on with the VVT hub pre-loaded clockwise to its limit - while making sure the cam orientation at the back end didn't move. The symptoms were pretty darn similar each way. I got quite an abundance of codes during scanning: P0238, P0118, P0236, P0103, P0452, P0134, P0014 and, finally, P0113.I should point out that I also put a new head on the car, because the previous one had been warped out of machinable spec. I also ran a compression test after installing the replacement head, and got reading from cyl's 1-5 of 150 psi, 137 psi, 130 psi, 135 psi, 150 psiBut the issue that strikes me as odd is the relationship between the throttle and the brakes. I could understand a GENERAL driveability issue or rough running engine due to the codes of the compression variance. But why the brakes knock the revs down to idle is a head-scratcher. How are the throttle and brakes interrelated?Joe Link to comment Share on other sites More sharing options...
Fran9690 Posted August 6, 2015 Report Share Posted August 6, 2015 Car does weird stuff when it goes into limp mode, throttle is drive by wire, not an actual linkage like on 98 and older. Hubs need to be fully oriented clockwise, timing marks will line up with marks on the cover this way. Some of those codes you listed are related to the MAF. A bad mass air flow can cause driveability issues/rough running. Maybe try swapping in a new one and see what that does or unplug it and see if it runs better that way? Also got an ECT sensor code, bring up the PID and see what it's reading. I've had it where it read that it was -40 degrees fahrenheit in the middle of summer, so it dumps fuel into engine like it's having a real cold start, making it run rough as well. You got a lot of codes, might be better off clearing your codes and pulling the ECM to reset adaptives and see what codes come back after. Link to comment Share on other sites More sharing options...
inetadv Posted August 11, 2015 Author Report Share Posted August 11, 2015 Thanks very much for your reply.I'm aware of the drive-by-wire - first year of a VERY poorly designed system. I've already replaced the gas pedal once before on this car when the mechanical contacts got worn and it went into limp mode. But the engine was running fine right before I had to replace the head. I've tried cleaning and unplugging the MAF - no change. I've cleared the codes and ran the engine for a while. Some codes were gone but many of the same ones were still there.What about the interaction between the brake pedal and the engine rpm? Why would touching the brakes knock the revs down to idle and prevent ANY throttle response as long as the brakes are applied? (Release the brakes and the engine revs) I can't find an answer to that ANYWHERE, and calling a Volvo dealer, or two or three, was of no help!Joe M Link to comment Share on other sites More sharing options...
Volvo5.0 Posted August 11, 2015 Report Share Posted August 11, 2015 Sounds like a problem in the ETM, wiring, or pedal position sensor. Probably not the pedal sensor, since you already replaced that. One of the tests to see if an ETM fault is active or intermittent is to press the gas pedal at the same time as the brake pedal. If there is an active fault the gas pedal is ignored when braking.Funny that after calling a few dealers, no one was able to answer that for you. Although that system hasn't been used for quite awhile. Link to comment Share on other sites More sharing options...
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