No power after braking Topic is solved

Cammer · Post by **Cammer** » 29 Oct 2018, 15:58

Thank you to anyone who has stuck with me through this! No power issue is till occurring after after short runs (about 250 yds or so). Everything seems ok (the engine starts fine warm and cold) try to accelerate - no power but continues to run; turn the engine off; restart right away and it powers on for another short distance. Here’s what I’ve done so far: new front oxygen sensor, new throttle position sensor, new cam position sensor, cleaned throttle body, new fuel filter, cleaned MAF, replaced vac lines to air box, pinched off brake vac line (no difference) checked vacuum lines and fittings with “ear & rubber hose” and carb cleaner spray, checked and lubricated idle air motor. Still goes into no powder mode… But now on restart, idle fluctuates regularly between 1100 - 1400rpm. Any other ideas or suggestions are appreciated.

Cammer · Post by **Cammer** » 29 Oct 2018, 16:02

Thank you to anyone who has stuck with me through this! No power issue is till occurring after after short runs (about 250 yds or so). Everything seems ok (the engine starts fine warm and cold) try to accelerate - no power but continues to run; turn the engine off; restart right away and it powers on for another short distance. Here’s what I’ve done so far: new front oxygen sensor, new throttle position sensor, new cam position sensor, cleaned throttle body, new fuel filter, cleaned MAF, replaced vac lines to air box, pinched off brake vac line (no difference) checked vacuum lines and fittings with “ear & rubber hose” and carb cleaner spray, checked and lubricated idle air motor. Still goes into no powder mode… But now on restart, idle fluctuates regularly between 1100 - 1400rpm. Any other ideas or suggestions are appreciated.

Post by **erikv11** » 29 Oct 2018, 16:23

Cleaning the MAF is rarely productive, however you can do a free, very easy and very good diagnostic test as suggested in a previous post by Sommerfeldt.

With the car off unplug the MAF. Then start it up and see if that addresses the problem.

Sommerfeldt · Post by **Sommerfeldt** » 30 Oct 2018, 06:24

It's always a bad idea to throw parts at these cars before knowing what the issue is - as in, it gets expensive really quickly. On the other hand, you've probably replaced some things that were 20 years old, so you can always clock it up to preventive maintenance.

Cleaning the MAF, as erikv said, rarely does anything. Your 512 code suggests the MAF is either giving up or on its last legs, so do the test before going further. Remember not to unplug/plug in stuff while the engine is running.

Turn the car off, unplug MAF, start car.

Like I said, this will result in the car running rich, but not to the point of backfires or loses power - at most, the exhaust will smell like bovine droppings and be black-ish. Btw - silly thing, maybe, but check carefully that the hose from airbox to intake is fastened securely and is tight.

- S

Post by **jimmy57** » 30 Oct 2018, 10:39

Is this a 10 valve motor that uses MAP sensor connected to intake or a 20 valve with MAF? A MAP sensor can go whack-o with high vacuum and cycling key resets the MAP tables in ECM.

Cammer · Post by **Cammer** » 30 Oct 2018, 11:31

I’ve had, previous to this car, 3 - 850’s all with a MAF sensor attached to the air intake hose. This one has an AIT sensor in that hose. I believe the MAP is below the radiator cowling attached to the intake manifold by a thin vac line. The valve cover has DOHC on it (I’ve wrongly assumed that the engine is a 20 valve) but with your insight I now figure it’s a 10 valve. Feeling very dumb! It’s no wonder I couldnt find the MAF sensor

. I’ll try to find a test for the Map sensor and let you know what happens …

Post by **erikv11** » 30 Oct 2018, 14:56

Is your car's IAT on the snorkel tube? viewtopic.php?f=1&t=87167

I am useless once we start talking 10 valves ...

Cammer · Post by **Cammer** » 30 Oct 2018, 16:18

Yes, the IAT fits through a hole in the top of the snorkel. I’ll test out the IAT and the MAP sensor tomorrow, (found some methods to test them out). I feel dumb that I didn’t realize it was a 10 valve, before trying to diagnose the difficulties it’s been having. Thanks again

Sommerfeldt · Post by **Sommerfeldt** » 31 Oct 2018, 06:20

Uh. I thought you said you cleaned the MAF.
Are you sure it's a Volvo?

- S

Cammer · Post by **Cammer** » 31 Oct 2018, 09:16

It was the AIT that I cleaned

. Just checked…Yup it’s a Volvo!

No power after braking Topic is solved

Re: No power after braking