2002 XC70 intermittent loss of throttle control

[Jpm53]

Hi everyone,
I'm new to this forum although I have used it to troubleshoot the many problems I have had with this car since I bought it about three months ago. I am now 1,000 miles from home and have a new problem. Intermittently, when I come to a stop, when I go to accelerate I get no throttle response. I shut off the engine then restart it and everything works fine. From what I have read about the best ETM problems, this doesn't seem to be a symptom of an ETS failure and I have not been able to find anyone else reporting this particular problem. Only happens when I come to a stop (so far) engine is not surging or running rough. Only other thing is occasionally stalls at idle. Anyone have any ideas?

Thanks for any help you can provide.

[howardc64]

Most ETM problems are 99-01. 02s are more reliable (Its a Bosch design. I've read it has 2 internal ETS. One is resistive (basically a potentiometer) and the other one is magnetic contactless). 99-01 ETM has 2 resistive ETS that wears out at about 100k miles. Not to say you don't have an ETM problem, just much less likely than the 99-01s you read about.

I assume no CEL?

I've had a random throttle response loss for few seconds that eventually turned into random engine shutdown when coming to a stop. Had no CEL, culprit was MAF. Found it by swapping MAF with another car. Kind of a pricy part to throw at the problem. If you do get a MAF, get a Bosch and avoid cheaper aftermarkets.

[Jpm53]

Yeah, no CEL just little or no throttle response. Once when it did this I had a little increase in engine rpm with the throttle all the way to the floor.

Have read that the MAF can cause throttle problems. May try that and see what happens after I check all the vacuum lines and connectors again.

Thanks for your help,, was not aware that the ETM on the 2002 was more reliable. I

[El Rollo]

Try resetting the throttle body .

[Astro14]

Have you checked the basics? Ensured that the connection of the wiring to the throttle body is clean/tight/intact?

[Xfingers]

So it happens intermittently. I'd be curious if when you come to a stop you were to put the car in P or N, and then you stepped on the accelerator would you still get no throttle response, no engine revving? Could this be a possible scenario: You come to a stop, you shift to N, you rev the engine a little, you shift back to D, and no throttle response? Guess I'm trying to determine if the transmission has a role in any of this. If the tranny was dropping out of gear when coming to a stop, upon acceleration I would think you'd hear the engine rev (throttle response) even tho you wouldn't move. Unless the engine was going into some kind of shutdown mode/safety response which clears on a restart. How's the level on your ATF? Transmission software update?
Just throwing things against the wall here...

[hoonk]

I'm new to this forum, I bought it about three months ago. I get no throttle response.

Are you certain you own a 2002? What brand of throttle module is on your car - magnetti marrelli (sp) or bosch? What are the results of a scan w VIDA? Bosch throttle problems can sometimes be fixed with replacement connectors at the throttle - 30656679

[Jpm53]

Yeah, checked everything but will check again just to be sure.

Thanks for your reply.

[Jpm53]

VIN says 2002. What is the easiest way to determine which throttle module I have? Have not had aVIDA scan done yet since the problem just started yesterday. Will look into the connectors.

Thanks for your reply.

[Jpm53]

Will try putting it in P or N and check the throttle response next time it does it. Don't think it is the transmission. The transmission was bad when I bought the car. Turned out to be a cracked C1 clutch drum. Did a complete rebuild including case mods and rebuilt converter. Had the software updated and the relearn procedure done by the dealer. Transmission has been working fine. That's not to say that it couldn't be the transmission, failure after repair is always an option.😏 Fluid level is correct.

Seems to be a throttle problem though. I try to accelerate and the engine just stays at idle until I shut it off and restart.

Thanks for the reply. Every idea helps.

[Jpm53]

How exactly is that done? Is it the same as an ECU reset where you disconnect the battery for 10 minutes and reconnect?

Thanks for your help.

[hoonk]

What is the easiest way to determine which throttle module I have?

The marelli has a black cap on both ends of the throttle shaft, and is more rectangular like the parts drawing,
7944
The bosch has a black cap on one end and is almost square.

[Jpm53]

Hi again,
Here's the latest on my throttle problem. On Monday, I replaced the MAF and had the battery disconnected while I did it so guess I also did an ECU reset inadvertently. Drove the car all day Monday and Tuesday without incident until the end of the day on Tuesday when it started stalling when I came to a stop. Parked it overnight then drove it Wednesday and Thursday with only one or two stalling incidents. Started driving it today and had two stalling incidents and two episodes of loss of throttle control.

I also noticed that it seems to be idling low -700rpm in P,N and D. Starting to think it is the ETM after all. From what I can see, looks to be a Bosch ETM. Talked to an Indy Volvo mechanic and he said it sounds like a gunked up ETM so I guess that will be my next project when I get home.

Thanks for all your help everyone.

[El Rollo]

Is worth to try he reset of the TB, with key on ll position press the accelerator pedal slowly all the way down, twice. I know is along shot but that took care of some delays we had with throttle response. Also make sure to check TB connections and possibly clean the butterfly...
Good luck

[Aussie70]

I had this exact problem for at least 6 months.
had the codes read at the dealer & there was one for low voltage or something at the maf.

they also load tested the battery & said that it failed - I had never had a problem starting the car. Anyway I tried cleaning the maf sensor a few times, considered buying a new one & the problem of a massive flatspot when taking off from a stop kept happening.

what definitely solved it was a new battery.