I've owned this 2001 V70 2.4T since 2007. Currently has 136k. Had virtually zero work to do on the car over the years (both control arms, a plug coil here and there, and basic maintenance: s-plugs, oil, filters, etc. …)
So the current problem is the following codes and involves a lengthy couple months of replacing bits including the ETM.
Current codes:
ECM-910E Throttle unit, internal fault. Faulty signal.
ECM-902A Throttle unit communication.
ECM-959F Electronic throttle module (ETM), internal fault. Faulty signal.
ECM-903F Throttle unit, internal fault.
The long story starts here for full two month background, if you want to skip down to the juicy bits look for: Beginning of ETM fun: it'll save reading through the background and lead up.
So we all know the common symptoms to an emergently failing ETM: surging, rough idle, some TPS error codes (p-0121, etc) that are intermittent and non-direct to the ETM. These all started in late August, 'bout two months ago. I've searched all the usual Volvo sites and have read and reread everything related to ETMs on this model and year. Forgive the following novel but in my observation the best threads are those that start with a thorough accounting of the issue and recent history.
Following is a list of everything I've done since the beginning of September when I undertook a comprehensive maintenance interval; I've noted where I began working the ETM problem but have included the basic stuff I was undertaking prior just so we can all cross those off the list as these play into issues following the install of the xeModex ETM rebuild.
Sept 06:
-replaced all spark plugs & ignition coils
-fuel filter & air filter
-timing belt
-water pump
-coolant flush replaced upper and lower hoses
-oil change, with filter
-(also replaced front brake hoses, and bled brakes…but that can’t have anything to do with it!!
Following this service work we traveled to my sister's driving 350 miles nonstop. Ran great, noticed slight throttle hesitations a couple times but had 28.8 mpg and smooth running. We pulled off highway, drove around city for 10 mins, stopped, ran into grocery store, then drove 10 mins to sister’s house) upon pulling into driveway the “no oil pressure” light flashed on. Stopped car immediately. Let sit for an hour, turned on and checked error codes; there were no error codes, no return of the low/no pressure light. Drove the car around her neighborhood to see if I could get the pressure light back once it was up to temp. Nothing. Fluids all good. So, the car sat for a day and then drove beautifully 350 miles home. No problems.
Couple days later throttle hesitation resumed and idle became real rough with a visible hesitation in the upper range too. I checked again for error codes and out came:
P-0121 - Throttle Position Sensor/Switch A Circuit Range/Performance Problem
P-0021 - “A” Camshaft position-timing over-advanced, or system performance [bank2]
Ooops
missed a tooth on the exhaust cam when I did that timing belt. Nuts. Researched that to death and fixed the error. Cleared the code and tried a test drive. Terrible. Idled great at first but under load hesitated, missed…just ran like crap. Code P-0121 came up right away and there has been no return of the P-0021. (timing looks great on the Autel) So I began the process of doing the pre-elimination work before the ETM replacement. After each move I'd reassemble, restart, limp around the block to catch a code before moving to the next. The code for the Throttle Position returned after each of the following.Beginning of ETM fun:
1) PCV—entire system replaced including insulated coolant line.
2) all vacuum hoses replaced and all fitted with new clamps spec'd to hose size.
3) cleaned MAF
4) pulled ETM (factory original white label), cleaned (rather gummy), refit with some high temp RTV on the old gasket (just incase as I had read an air leak was likely with a gasket reuse). Cured overnight.
Ran nice at initial idle at start up. Then same as above, 500 feet driving, missing feel, hesitation (started getting scared that I'd bent a valve or worse with the Timing Belt screw up
) went ahead and ordered new ETM from XeMODeX and planned for a compression test.5) ETM replaced with XeMODeX rebuilt unit, coded to car…supposedly…really (? beginning to wonder, impossible to know given that the problem has yet to be resolved). The ETM I replaced was factory original, white label. I removed the plenum to ensure that I cleaned off all the RTV before seating the new ETM gasket. Second time I removed the fuel rail and injectors, retaining clip on end of all injectors appeared worn and brittle, two broken, so I removed them and ordered injectors.
After #5 above, for about 5 minutes, it idled well, perfect in fact; after about 500 feet of driving, the engine sounded like it was missing. No acceleration, no power…back to limp-home-mode. So replaced the MAF.
6) replaced MAF, after cleaning it a second time, no codes suggesting it was failing but XeMODeX's literature require it to be, presumed to be failing. Both old and new test in spec on the Autel reader.
After the MAF was put in, the car started beautifully, idled perfectly 850-900, left car to run and reach operating temp but it stalled before it got halfway to operating temp. Started the car back up, the rough idle had returned — similar to ETM issue except it did allow me to run the engine up to 4K in park: apparently out of limp mode? Nope. Tried a drive and back to limp mode, but in P (park) throttle seemed responsive upon start up of cold engine. Tried this multiple times with the same results; good on cold, bad on operating temp, in limp-mode under both. After the MAF though I'm not getting any DTC codes popping.
So…time for that compression check!
Compression test returned great numbers. Checked spark plug gap when I did compression, all perfect. Checked all those new coils, perfect, with good resistance. Inspected ignition wiring and plugs, all good.
In order to eliminate everything else I could think of I have now done:
7) vacuum smoke test: a balloon pump, incense, and some clear tubing! no leaks found, verified at multiple points, system was well primed.
went through XeMODex's ETM flow chart to check their unit. Electrical passed (num7 fuse pull and replace activates ETM, check fuse bay and harness continuity, ECU relay: all good). Already did MAF, but went ahead and did a continuity test at harness plug, good. 9) Replaced injectors (just being overly thorough and anticipatory), inspected wiring, all good. Also checked fuel system pressure, steady at 50psi dropping to 43psi with ignition off after 30 mins.
10) Checked all intercooler hoses for the umpteenth time, replaced a couple hose clamps. Everything’s tight and sound.
So…what am I missing?
Send ETM back to XeMODeX? Anyone had experience with this?
Kinda at a loss, looking forward to the help.
Current codes, again:
ECM-910E Throttle unit, internal fault. Faulty signal.
ECM-902A Throttle unit communication.
ECM-959F Electronic throttle module (ETM), internal fault. Faulty signal.
ECM-903F Throttle unit, internal fault.
