PDA

View Full Version : Weak starts, weird idle, fuel smell



rockbeau25
04-13-2017, 05:26 AM
Like the title says, I've been having these issues with my car. Randomly, when I try to start it, it barely starts. Eventually it sputters to life. When it finally starts, it idles weird; the RPMs fluctuate on its own, sometimes going as high as 2500 rpm. This whole time, it smells strongly of fuel. When I scanned my car, the only codes I got were for an o2 sensor (replaced already, and coolant temp sensor. Looking for some insight as to what this could be. Some of my friends suggested PCV

thedanplasse
04-13-2017, 06:21 AM
Did you check your maf?

Bordom
04-13-2017, 09:02 AM
Unplug MAF and report back

Sent from my SM-G935W8 using Tapatalk

Davdraco1
04-13-2017, 09:19 AM
What's the code for the CTS?

rockbeau25
04-13-2017, 09:23 AM
Did you check your maf?


Unplug MAF and report back

Sent from my SM-G935W8 using Tapatalk

Problem is it's random so it might be a few days before I know

Cactus Avant
04-13-2017, 08:22 PM
You aren't leaking any fuel while the car is on, are you? When my car began to leak fuel I could smell it, but couldn't see any leaks immediately. It took a little while until it started dripping in the rear. Sometimes it wouldn't happen for a while either. Since you can smell fuel, I'd first try to inspect all your fuel lines to see if you have an issue with those. Does the problem have anything to do with the temperature outside? Only happen when its warm or only when its cold?

rockbeau25
04-13-2017, 08:31 PM
You aren't leaking any fuel while the car is on, are you? When my car began to leak fuel I could smell it, but couldn't see any leaks immediately. It took a little while until it started dripping in the rear. Sometimes it wouldn't happen for a while either. Since you can smell fuel, I'd first try to inspect all your fuel lines to see if you have an issue with those. Does the problem have anything to do with the temperature outside? Only happen when its warm or only when its cold?

I have not been able to find any correlation. The fuel smell is only when it starts

Mattr567
04-13-2017, 08:36 PM
Replace the coolant temp sensor, it messes with the engine management and it runs too rich. Its hunting (rpms fluctuating) because lambda is not in control of the mixture. It can't attain proper closed or open loop.

Do you have a black coolant temperature sensor? That is the early version which is defective. The new one is green.

kjames1270
04-13-2017, 08:58 PM
Coolant temp sensor would affect fuel delivery?

Sent from my A0001 using Tapatalk

Mattr567
04-13-2017, 09:06 PM
Coolant temp sensor would affect fuel delivery?

Sent from my A0001 using Tapatalk

For example if the coolant temp sensor is telling the car its -10, the cars gonna run too rich. Who knows what its actually telling the car, there's a code for a reason.

It's probably doing a cross check and finding a discrepancy between what the coolant sensor is saying and some other sensor.

thedanplasse
04-14-2017, 04:58 AM
CTS does some weird shit to these cars. But I'd check that MAF too.

walky_talky20
04-14-2017, 08:50 AM
The coolant temp sensor is very heavily relied upon for fuel mixture on pretty much all cars with electronic fuel injection. A bad reading from the coolant temp sensor can make the fuel mixture so far off that the car won't even start. Even the green sensors will fail in all sorts of ways. Most of the time it won't even throw a code, but if it does, the sensor is almost definitely junk.

You can do the same unplug trick with the CTS if you want. The ECU will use a default value of 70c (158F) which should allow it to start and run decently unless maybe its super cold outside. This is a handy parking lot fix if you're stranded. A better diagnostic approach would be to look at the Coolant Temp value in the ECU (not the cluster) with VCDS at cold start.

The OP's symptoms are pretty textbook CTS failure. They are known to be intermittent like that. A MAF, on the other hand, will generally be dirty or not. They don't usually cause intermittent problems at startup.

kjames1270
04-14-2017, 10:39 AM
The coolant temp sensor is very heavily relied upon for fuel mixture on pretty much all cars with electronic fuel injection. A bad reading from the coolant temp sensor can make the fuel mixture so far off that the car won't even start. Even the green sensors will fail in all sorts of ways. Most of the time it won't even throw a code, but if it does, the sensor is almost definitely junk.

You can do the same unplug trick with the CTS if you want. The ECU will use a default value of 70c (158F) which should allow it to start and run decently unless maybe its super cold outside. This is a handy parking lot fix if you're stranded. A better diagnostic approach would be to look at the Coolant Temp value in the ECU (not the cluster) with VCDS at cold start.

The OP's symptoms are pretty textbook CTS failure. They are known to be intermittent like that. A MAF, on the other hand, will generally be dirty or not. They don't usually cause intermittent problems at startup.
Thanks for the explanation, I would of never suspected the cts. I'll try this next

Sent from my A0001 using Tapatalk

rockbeau25
04-14-2017, 10:41 AM
Thank you Walky! The I know the CTS in on the coolant flange but where exactly. I popped my hood and looked not very closely and didn't see it.

walky_talky20
04-14-2017, 12:11 PM
This is the location:

http://i1030.photobucket.com/albums/y364/bizkitalex/P1050489.jpg

You have a ReflectTuning chip, so I'm assuming your car is a 2001. So it will be less accessible than the picture due to a breather hose on the valve cover and the Secondary Air Injection "Combi" Valve on the back of the cylinder head. But it is possible to unplug it. A small screwdriver and a good understanding of how the connector latch works are all that is needed.

prkieffer
04-14-2017, 12:56 PM
High pressure fuel line. I had to replace mine. Don't drive or start it it was leaking fuel on the engine AOA covered the repair because I forced them to because it was a safety issue and I could see the fuel dripping on the engine. Right behind the engine near the firewall.


Sent from my iPhone using Audizine (http://r.tapatalk.com/byo?rid=87676)

rockbeau25
04-14-2017, 12:58 PM
This is the location:

http://i1030.photobucket.com/albums/y364/bizkitalex/P1050489.jpg

You have a ReflectTuning chip, so I'm assuming your car is a 2001. So it will be less accessible than the picture due to a breather hose on the valve cover and the Secondary Air Injection "Combi" Valve on the back of the cylinder head. But it is possible to unplug it. A small screwdriver and a good understanding of how the connector latch works are all that is needed.

Nope, 1999 AEB, pre facelift

thedanplasse
04-14-2017, 01:11 PM
Just dont zing that clip into the abyss lol.

rockbeau25
04-15-2017, 03:13 PM
https://uploads.tapatalk-cdn.com/20170415/b7150a01b045e93549104e9bcd5e9fb1.jpg

Is this blue thing it?

kjames1270
04-15-2017, 03:24 PM
https://uploads.tapatalk-cdn.com/20170415/b7150a01b045e93549104e9bcd5e9fb1.jpg

Is this blue thing it?
It has connectors like that exposed. There's a clip holding it in place down more, easy to lose. After just Unscrew and pull. Just got 2 from a junkyard today.

Sent from my A0001 using Tapatalk

walky_talky20
04-15-2017, 07:44 PM
Yes, that is it.

TheRedGlacier
04-16-2017, 02:28 AM
If not the CTS, a bad fuel pump is a possibility. Also, when was the fuel filter last changed?

rockbeau25
04-16-2017, 07:12 AM
If not the CTS, a bad fuel pump is a possibility. Also, when was the fuel filter last changed?

Before my ownership