[SOLVED] Heat Soak no start P2

[reVolvR]

Hi There,

I have been chasing this issue for over a year now with limited success for my 2004 Volvo S60R (manual).

CaR will start fine when cold and run fine. Turning off when hot and starting again immediately after (within ~1 min) will start fine. After it has heat soaked (1-30 min after being turned off), the engine will crank and crank, sometimes jumping in RPMs like it is about to start, and never does (but sometimes will if I am lucky). Starts fine again after cooling down a bit ~30+ min later. Doing a push start while heat soaked also works, runs fine after it is started. Air/fuel ratio is good while running (around 14.7 normal load, 12-13 WOT).

It used to idle fine while having this issue, but recently it has started to have idling troubles, even while cold. I think this may be a different issue though since it was originally having heat soak no start issues while idling well. Now, It gradually goes rich (AFRs go from 14.7 to 12 over 3 seconds), loses RPMs and goes lean rapidly (16+) just before recovering and idling normally again.

I have tried replacing:
Crank position sensor
Starter
Spark plugs - fixed the issue for several months, now it is back. Might try re-gapping the plugs.

This forum post noted similar symptoms for a '98 V70, but no solution. They tried replacing many more parts than I have: viewtopic.php?t=81617

Current Mods:
"Cold air" intake filter (hot air at the moment, need to re-make my airbox. Lost the OEM airbox/filter)
Manual boost controller
Resonator-back aftermarket exhaust
Kevlar wrapped around charge pipe for heat management
Gauges to monitor AFRs, boost pressure, and battery voltage

Any ideas would be greatly appreciated!

SOLUTION:
After replacing the MAP (Mass Air Pressure) sensor on top of the intercooler, I have not had any more issues with hot starts over the past month.

[volvolugnut]

I had a similar problem on 2001 V70 T5 and solved by replacing the ETM with Exemodex. You should have the the improved later ETM I think, but maybe not. Search ETM here for lots of info.
volvolugnut

[jonesg]

Theres harness that runs behind the starter which can give hard hot starts, moving it away from the starter helps, its known to pick up RF interference. It might be the crank position sensor wire.

[darylrobert]

i had this, mine turned out to be the ignition key imobilizer ring, it cranked and cranked after a short drive on hot days. However it can also do it if you have low compression.

[abscate]

The 2004 is known for having a CEM heat soak issue in warm climates - there ar threads on that and adding a heat sink as a solution

[reVolvR]

Thank you all for the replies, I finally had some time to try some new fixes. I believe I fixed my rough idle problem today by replacing the fuel pressure sensor and removing the blowoff valve which had a bad seal. Logging fuel pressure with VIDA showed some large spikes in fuel pressure randomly and no increase in fuel pressure occasionally during pulls with the old sensor.

I am hesitant to say the hot start issue is a problem with the CEM, ETM, or ignition immobilizer ring. The fact that it starts fine directly after long, spirited drives makes me think the problem is with a part that is being actively cooled when the engine is running. Once it is not being cooled by coolant, fuel, or air and has a chance to heat up for a few minutes while not being cooled is when it stops working.

I do see tach jumps occasionally while it has trouble starting, which probably means the starter motor is inducing a current in the crank position sensor wires. When I got the car, the wire was sitting on top of the starter motor instead of behind it against the block. I moved the crank position sensor wires to behind the starter motor against the block where it is supposed to be, but this did not help. I have tried looking up if it is possible to build a faraday cage around the wire, but reading around on the forums here, the people that have tried did not succeed. The crank position sensor is new and this problem started a long time after I got my clutch replaced, so I don't think the flywheel is loose (plus it runs fine).

I am thinking potentially a bad MAP sensor or cam position sensor? Pouring water over the cam position sensor does not help though. Are there any other sensors in the engine that are actively cooled by coolant, fuel, or air?

Thanks

[darylrobert]

Try this, remove the ignition immobiliser from the ignition and hit it with a heat gun to simulate a hot day, place back in position and try starting. Have you ever seen the message "start inhibited please try again" after many months of starting issues my car only displayed this once but it was a clue.

[jonesg]

Thank you all for the replies, I finally had some time to try some new fixes. I believe I fixed my rough idle problem today by replacing the fuel pressure sensor and removing the blowoff valve which had a bad seal. Logging fuel pressure with VIDA showed some large spikes in fuel pressure randomly and no increase in fuel pressure occasionally during pulls with the old sensor.

I am hesitant to say the hot start issue is a problem with the CEM, ETM, or ignition immobilizer ring. The fact that it starts fine directly after long, spirited drives makes me think the problem is with a part that is being actively cooled when the engine is running. Once it is not being cooled by coolant, fuel, or air and has a chance to heat up for a few minutes while not being cooled is when it stops working.

I do see tach jumps occasionally while it has trouble starting, which probably means the starter motor is inducing a current in the crank position sensor wires. When I got the car, the wire was sitting on top of the starter motor instead of behind it against the block. I moved the crank position sensor wires to behind the starter motor against the block where it is supposed to be, but this did not help. I have tried looking up if it is possible to build a faraday cage around the wire, but reading around on the forums here, the people that have tried did not succeed. The crank position sensor is new and this problem started a long time after I got my clutch replaced, so I don't think the flywheel is loose (plus it runs fine).

I am thinking potentially a bad MAP sensor or cam position sensor? Pouring water over the cam position sensor does not help though. Are there any other sensors in the engine that are actively cooled by coolant, fuel, or air?

Thanks

its a known problem, starter induces RF in the CPS wire, removing it from behind the starter is a common fix, you unfixed it.
They sell that wire, but a long term fix for some owners is to replace the starter.

[vtl]

99% it's the starter, as others already said.

[reVolvR]

Thank you all for the replies, I finally had some time to try some new fixes. I believe I fixed my rough idle problem today by replacing the fuel pressure sensor and removing the blowoff valve which had a bad seal. Logging fuel pressure with VIDA showed some large spikes in fuel pressure randomly and no increase in fuel pressure occasionally during pulls with the old sensor.

I am hesitant to say the hot start issue is a problem with the CEM, ETM, or ignition immobilizer ring. The fact that it starts fine directly after long, spirited drives makes me think the problem is with a part that is being actively cooled when the engine is running. Once it is not being cooled by coolant, fuel, or air and has a chance to heat up for a few minutes while not being cooled is when it stops working.

I do see tach jumps occasionally while it has trouble starting, which probably means the starter motor is inducing a current in the crank position sensor wires. When I got the car, the wire was sitting on top of the starter motor instead of behind it against the block. I moved the crank position sensor wires to behind the starter motor against the block where it is supposed to be, but this did not help. I have tried looking up if it is possible to build a faraday cage around the wire, but reading around on the forums here, the people that have tried did not succeed. The crank position sensor is new and this problem started a long time after I got my clutch replaced, so I don't think the flywheel is loose (plus it runs fine).

I am thinking potentially a bad MAP sensor or cam position sensor? Pouring water over the cam position sensor does not help though. Are there any other sensors in the engine that are actively cooled by coolant, fuel, or air?

Thanks

its a known problem, starter induces RF in the CPS wire, removing it from behind the starter is a common fix, you unfixed it.
They sell that wire, but a long term fix for some owners is to replace the starter.

Unfortunately, the starter is new and I tried moving the CPS wire to its original position next to the block when I replaced the starter motor (this problem was happening when I had the old starter motor and the CPS wire was routed over the top of it). Maybe I will try moving the CPS wire again. Where is the best place to move it to? It seems like moving it so it is draped over the top of the starter motor would be even worse, but I am not sure if it is long enough to reach anywhere else.

Try this, remove the ignition immobiliser from the ignition and hit it with a heat gun to simulate a hot day, place back in position and try starting. Have you ever seen the message "start inhibited please try again" after many months of starting issues my car only displayed this once but it was a clue.

I have not seen that message, and my problem persists even on cold winter days. I would think that if this was the problem, it would not be able to start as soon as the car turns off if it is hot. It still starts within ~3 minutes of being turned off, so it has to be a part that is being cooled (or is connected to something that is being cooled).

Thanks for your help.