Help! help! help! My S60R struggles to start when hot

[Ruboduncan]

I have a 2004 s60r and when it's hot it swings and swings and swings for like a minute befor it starts. It's starts 1st time when cold. Please help!!!!!! Iv been struggling for over a year with this problem. Car has been from tech to tech and workshop to workshoP and they all jst give up eventually. I haves charged plugs, fuel pump, did the rings, u name it. I'm now at a point where I'm hating this car. I haven't driven it except to test it after every Machanic, same problem. Even Volvo has no answer. Please helP!!! I will do anything. Please please, I'm desperate

[vLGrok]

Stock? List Mods.

[doubleb26]

Where are you located?

[swede2nr]

I'll wager a guess- coolant temp sensor?

[thegrapist]

"Did the rings"? I'm assuming you don't mean the piston rings.

Next time your car doesn't start get a bottle of cool water and spray some on the cam angle sensor, if it starts afterwards you have your answer. If you aren't sure where that is, check out the pictures in the first post:

http://volvoforums.com/forum/volvo-s...ken-cap-46400/

Also (unlikely, but worth a try) check the coils for spark next time it acts like that.

[thegrapist]

I'll wager a guess- coolant temp sensor?

No way. The car will still start if the coolant temp sensor is all over the place (and if you unhook it). There's most likely a sensor that's overheating/ not doing it's job that's directly related to the basic engine operation. My guess would be to check to make sure to check the cam sensor and the crank position sensor first. Cam angle sensors commonly freak out when they get to hot. Plus they make it difficult to start.

[rogersampson]

How is the cranking speed when it is hot and will not start? Does it seem to crank slower or faster when hot?

You mentioned rings, which rings and what led up to their replacement? Has there been a compression check?

Is it a flat no start or does it sputter a bit and then come to life?

As stated by others, I am suspecting the crank position sensor, they tend to fail on a hot engine, but fine when cold.

A more remote guess is fuel pressure sensor.

Has there been any diagnostics run and codes that you could share?

[Ruboduncan]

Hi, stock

[Ruboduncan]

I'm in South Africa

[Ruboduncan]

I'll wager a guess- coolant temp sensor?

I will check and let u no thanks

[Ruboduncan]

Thanks I will try it. Yes I meant piston rings, sum1 sed that it could be compression rings.

[Ruboduncan]

The car has been on the computer and all faults are clear, where does the cam sensor sit. Would it not have brought up a fault

[Ruboduncan]

Hi, it swings and swings and pics up gradually starts to fire up after many turns. Computer shows no faults. How can I test this crank sensor that u talking about? And why doesn't it show a fail when the put it on the computer. They did do a compression test. What are the readings to be. This the reason I did the ringe

[Ruboduncan]

Cranking speed is slow when hot

[thegrapist]

Hi, it swings and swings and pics up gradually starts to fire up after many turns. Computer shows no faults. How can I test this crank sensor that u talking about? And why doesn't it show a fail when the put it on the computer. They did do a compression test. What are the readings to be. This the reason I did the ringe

compression numbers don't matter as much as long as the numbers are the same across the board, unless they're significantly low. A leak down test is more useful than a compression check. You can pull good numbers on a compression check and have terrible leakdown percentages. More importantly, if you had leaky piston rings, it'd be worse when cold, not when hot.

You disassembled the whole motor, reused pistons, reused bearings, and replaced just the rings without checking any of the sensors? I told you earlier, when it's hot throw some water on the cam angle sensor. it's on the trans side of the cylinder head in that picture I posted above.

[Ruboduncan]

Hi
I reused the pistons but replaced rings and bearings.
Another tech mentioned that it could be that head may have been line bored and that results in the lifters not getting enough oil pressure and with continuous cranking it eventually gets enough presure built up and increases compression.
The previous tech says that he has checked the cam and crank sensors. Aparently he also through cold water. Said it was one of his 1st tests. Is there a way to test the fuel pressure sensor? How would a fuel pressure sensor cause this problem.
Thanks for trying to help me

[thegrapist]

I doubt it has anything to do with the motor itself unless you did a bang up job rebuilding the motor. If you really think it's a compression issue put a few drops of oil in your cylinders (through the spark plug holes). If it fixes it, then your rings are done. I'm 99% sure this is not your problem though. I don't know how to test a fuel pressure sensor since I'm not too familiar with any car that's ever had a fuel pressure sensor so I have no idea how the ecu processes that information. Because of that I can't provide you too much help on that front. All I can say is try hooking up the sensor to a pressure signal (air compressor) and taking voltage readings off it (assuming it is an analog sensor). I would read the service manual on that. But give that a try.

Also check the vvt mechanisms. If they're getting stuck or not working properly, that could definitely prevent the car from starting if they're going full retard on start.

I do vaguely remember reading something about throttle bodies going bad on these cars due to them having a brushed motor or something to that fact, so after a while they wear out. That might be worth looking at, but once again, just an idea, probably not your problem.

[DOHC]

I had warm start issues when my MAF was bad. I also had other symptoms as well, but after taking care of some vacuum leaks I still had a hard start when warmed up and limited boost(I assume you do not have a boost gauge, so you don't know if you have low boost) and the MAF finally fixed it.

[thegrapist]

I had warm start issues when my MAF was bad. I also had other symptoms as well, but after taking care of some vacuum leaks I still had a hard start when warmed up and limited boost(I assume you do not have a boost gauge, so you don't know if you have low boost) and the MAF finally fixed it.

Good thinking. Next time it won't start unplug the maf and see if it starts.

[DOHC]

I forgot to mention, my car would run extremely rich in my case. Noticeable odor just standing near the car since the MAF reading was so high @ idle. You should really have a smoke test performed as well if you haven't already.

[garbergtsi]

No way. The car will still start if the coolant temp sensor is all over the place (and if you unhook it). There's most likely a sensor that's overheating/ not doing it's job that's directly related to the basic engine operation. My guess would be to check to make sure to check the cam sensor and the crank position sensor first. Cam angle sensors commonly freak out when they get to hot. Plus they make it difficult to start.

you havent saw the ECT cause a no start before?? I have, numerous times.
CMP I agree with you....

BUT my best guess on this one is a problem with interference getting into CKP after the engine was redone....this is verrrry common.

OP - do you ever get the tach jumping when you are cranking the engine over, before it starts?

[thegrapist]

you havent saw the ECT cause a no start before?? I have, numerous times.

I don't know much about volvos. Just got mine a few months ago, the 850 2 years ago and have had no problems with the 850. How does that work? If the ecu has a safety threshold where it won't start if it's too cold or too hot, that makes sense. But unless it does, even if you run a hot motor on a cold start fuel enrichment map, it'll still run. Not great, but it'll do it's thing. If you run a cold motor on a normal operating temp fuel map, it'll struggle to start but it'll barely do it. Even when I unplugged mine, the car started and ran. Not well but it worked.

[garbergtsi]

I don't know much about volvos. Just got mine a few months ago, the 850 2 years ago and have had no problems with the 850. How does that work? If the ecu has a safety threshold where it won't start if it's too cold or too hot, that makes sense. But unless it does, even if you run a hot motor on a cold start fuel enrichment map, it'll still run. Not great, but it'll do it's thing. If you run a cold motor on a normal operating temp fuel map, it'll struggle to start but it'll barely do it. Even when I unplugged mine, the car started and ran. Not well but it worked.

Interesting. Volvo's are all I have ever worked on and I see this one a regular basis.

[Ruboduncan]

Hi garbergsti
Wats CKP?

[Ruboduncan]

Lol I used genuine parts only, but like I said before it made no difference.
But would the vvt system get stuck everytime when the car gets hot without fail.
Once again would the throttle boddies cause the car to swing and swing only when its hot.

[Ruboduncan]

The Cranking speed is slow and speeds up as it gets close to starting. It cranks slower when hot.
Rings was replaced cause someone said that the compression was a bit low ( what are the values to be)
Its flat and speeds up and speeds up till it starts.

[Ruboduncan]

The compression numbers were slightly different accross, but not significantly low. If the there was a leak wouldnt the car have smoked at the exhaust.

[Ruboduncan]

What is ECT?
What is a Tach jumping when cranking engine over before it starts?
Sorry if I dont Understand

[rogersampson]

The fact that the cranking speed gets slower with a hot engine is a bit of a weird one. Is it noticably slower? Normally a warm engine will crank a bit faster.

Following the slow cranking when warm, it could be a starter motor issue, if it really is slower. The armature can expand slightly, and bind on the field winding.

One way to validate this is to look at the starter motor currrent draw in Amps, on both a hot and cold engine. Higher on a hot engine is a clue. Do you have a way of measuring starter current? A poor second choice would be to measure battery voltage while cranking, both hot and cold engine. The voltage should not be lower during cranking on a hot engine, and really should be slightly higher.On all cases it should not be lower than about 10.5 Volts.

Clearly Crank Position and Cam positon sensors hould be suspected first.

Has the fuel pressure at the fuel rail been measured? Would be interesting to know those numbers on both a hot and cold engine.

[thegrapist]

Interesting. Volvo's are all I have ever worked on and I see this one a regular basis.

Super. Can you explain why that is?

[garbergtsi]

CKP = Crank Position Sensor.
The thing is about the CMP (Cam position sensor's) is that it will start without them....if they are disconnected it may crank 6 seconds or so then start, or start immediatly depending on how lucky the ECM is.
Does the tach ever jump up past 500 RPM when you are cranking the engine over?
I would check voltage drops to the starter....check the jump start terminal under the hood...ensure the connection is good, check the ground to the transmission and check the connection right at the starter.....possible starter as well. Is your battery passing a load tesrt? I have had slightly weak batterys cause no start and even some will set a CKP code due to this. These need to be cranking at a fast enough speed to get the ECM to give spark/inj pulse so you may be on to something there. ALSO, i have had these quite a bit get interference into the CKP signal causing slower than normal cranking speed...you can check that with a scope and is a good possibility if the engine/trans have been seperated. What are your compression #'s? Is your cam timing correct?

As far as the ECT, it seems like ECT is one of the bigger inputs for fuel control. I have had a slew of 800's and SVC70's have a very intermittent stall when coming down to idle caused by an intermittent ECT sensor. Its super common on S/V40's as well, but more for a total no start. I agree that if you totally disconnect the ECT it will go into a default and look at other signals to start OK, but if its reading off but not far enough to put the ECM into default it can cause a no start. Its not as common on the later vehicles but I have still had it happen.