Cadillac Owners Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 20 of 50 Posts

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #1 ·
Hey guys, I have an 08 CTS with the 3.6l DI engine. I just got the vehicle, and it was already in limp mode; the previous owner (who said he was an aircraft mechanic) was obviously out of patience for it. P0087 code. The high pressure pump has been replaced, as well as the fuel pressure sensor on the fuel rail. The low pressure fuel pressure was 55 psi or so with engine off and no drop when running. Engine runs well, and sounds good running, except it won't come out of limp. I will say it doesn't idle "perfectly," but it did have a few gallons of old smelling gas in it, I added 12 fresh gallons and it idles way better, and although still not perfectly, the shudder is barely perceptible. I disconnected the negative on the battery for a half-hour, and it starts and will rev up around 3000-3500, but then goes into limp mode after only a few seconds and down to 2500 or less. I am wondering if there is something else I should be looking at? I have read on here that I need to check the fuel rail pressure, and I need a scan tool for that, so I just ordered a bluetooth OBD2 and plan on getting the Torque app as soon as I get it.

Assuming the fuel rail pressure is actually low, what conditions would cause this? What else should I be looking at? The car doesn't smoke, but the exhaust does smell a little rich, and the oil on the dipstick has a faint gas odor. Could it be an injector stuck open, or partially open? How would I test for that without removing the injectors? If I have to remove the injectors I will just replace them.

If the fuel rail pressure wasn't actually low, what conditions have been seen that could cause the P0087 code to be thrown? What would need to be tested?

Just trying to understand everything that could cause this condition, and where I should go from here. I looked for obvious fraying on the wiring harness, but it looked fine. I read on the internet some mechanics suggesting looking at the cam lobes, but I wondered how common of a problem cam lobe wear actually was, considering it seems like the rest of the engine would be shot if the cam lobes to the HPFP were that worn. Just wanted to hear from you guys, I know you have seen things like this before on here, and may have some insights I haven't considered. Thanks ahead of time.
 

·
Registered
2009 CTS4 LLT White Tricoat
Joined
·
83 Posts
Go to Ebay and buy an electronic copy of the service manual. Make sure it has hyperlinks. It's the best $15 you will spend. Start there with the DTCs.
 

·
Registered
'93 SedanDeville 60 Special
Joined
·
730 Posts
Typical causes for low fuel pressure include a dirty fuel filter,

weak pump,
incorrect tank venting,
restricted fuel lines,
a clogged pump inlet strainer,
faulty electrical control.
Leaking fuel injector


Else problem with the DI controller which is controlled by the setting in the PCM

Just an example of a engine with DI you can see the low and high pressure commanded by PCM
Use a fuel pressure gauge off fuel rail or a good OBD scanner and driver the vehicle and see
it the fuel pressure is correctly being controlled

598385
 

·
Super Moderator
Go ahead, blame me. Everybody does 🙄
Joined
·
13,484 Posts
Odometer reading?
How long has the vehicle sat unused before you purchased it?
It could very well be an injector(s) issue. Some real-time data via a proper scanner would be super helpful.


If the previous owner was an aircraft mechanic, let's hope he doesn't deal with stalling engines.
 

·
Registered
2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
Joined
·
2,043 Posts
If the previous owner was an aircraft mechanic, let's hope he doesn't deal with stalling engines.
I doubt "aircraft mechanic" is any sort of qualification for diagnosing an engine that is at least a half-century newer.
 

·
Super Moderator
Go ahead, blame me. Everybody does 🙄
Joined
·
13,484 Posts
I doubt "aircraft mechanic" is any sort of qualification for diagnosing an engine that is at least a half-century newer.
The fact that he touted himself as such is an automatic disqualifier for me.
 

·
Registered
'14 CTS-V LongRoof; '16 ATS-V Sedan,' 04 Trailblazer 4x4; '10 CTS LongRoof gone but never forgotten
Joined
·
17,576 Posts
We get airline mechanic resumes all the time. All they can do is pop rivets. They have no clue what the custom sheet metal industry is about.
 
  • Like
Reactions: Nonsmiley

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #9 ·
Typical causes for low fuel pressure include a dirty fuel filter,

weak pump,
incorrect tank venting,
restricted fuel lines,
a clogged pump inlet strainer,
faulty electrical control.
Leaking fuel injector


Else problem with the DI controller which is controlled by the setting in the PCM

Just an example of a engine with DI you can see the low and high pressure commanded by PCM
Use a fuel pressure gauge off fuel rail or a good OBD scanner and driver the vehicle and see
it the fuel pressure is correctly being controlled

View attachment 598385
Thanks for the ideas. I did a pressure test on the low-pressure side, which seems to eliminate most of those causes. I don't think the DI 3.6 has a fuel filter, at least not one you can get to without dropping the tank. I also ordered a bluetooth OBD2, it just hasn't arrived yet. Thanks for the response, though. Good ideas to troubleshoot, that's what I needed.
 

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #10 ·
Odometer reading?
How long has the vehicle sat unused before you purchased it?
It could very well be an injector(s) issue. Some real-time data via a proper scanner would be super helpful.


If the previous owner was an aircraft mechanic, let's hope he doesn't deal with stalling engines.
Long, the odometer has 150,000 miles. Quite a few, but maybe there's a little meat left on the bone. I'm not exactly sure how long it sat unused, but I gathered at least a year, but maybe interspersed with some starting to troubleshoot, move it out of the way, etc. I have a bluetooth OBD2 ordered that hasn't arrived yet, and I was going to download the Torque app as some have suggested elsewhere on here. Perhaps I jumped the gun posting this but I was interested in some ideas to mull over in my head in the meantime.
 

·
Super Moderator
Go ahead, blame me. Everybody does 🙄
Joined
·
13,484 Posts
Long, the odometer has 150,000 miles. Quite a few, but maybe there's a little meat left on the bone. I'm not exactly sure how long it sat unused, but I gathered at least a year, but maybe interspersed with some starting to troubleshoot, move it out of the way, etc. I have a bluetooth OBD2 ordered that hasn't arrived yet, and I was going to download the Torque app as some have suggested elsewhere on here. Perhaps I jumped the gun posting this but I was interested in some ideas to mull over in my head in the meantime.
No worries- it always helps to gather as much intel as possible before diving into an inherited problem.
Keep us posted with your findings.
 

·
Registered
'93 SedanDeville 60 Special
Joined
·
730 Posts
Has to be a filter but suspect your correct that it is in tank :(

Keep in mind as I shown the fuel system controller has to be responding to the min and max fuel pressure to properly command the DIs as this is how GM made a small injector flow much larger when need be so scanner is needed to see if the controller is commanding low to high rail pressures.

Is common, esp older DIs to go faulty and leak

Hopefully you have a good OBD-II scanner that supports GM's enhanced PIDs as there is several of them for the DI fuel system like I use :

598394
 

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #13 ·
No worries- it always helps to gather as much intel as possible before diving into an inherited problem.
Keep us posted with your findings.
I will. Nothing is more frustrating than finding a topic that fits your scenario perfectly, only to find the OP never followed up to let anyone know the outcome. It might be a little bit before I receive the bluetooth OBD2, but as soon as I get it I'll check the fuel rail pressure and I'll know a lot more.
 

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #14 ·
Has to be a filter but suspect your correct that it is in tank :(

Keep in mind as I shown the fuel system controller has to be responding to the min and max fuel pressure to properly command the DIs as this is how GM made a small injector flow much larger when need be so scanner is needed to see if the controller is commanding low to high rail pressures.

Is common, esp older DIs to go faulty and leak

Hopefully you have a good OBD-II scanner that supports GM's enhanced PIDs as there is several of them for the DI fuel system like I use :

View attachment 598394
I just ordered the bluetooth OBD2, and some others in this forum suggested the Torque app for android to connect to it. I don't know if the app has those parameters or not, but I'm open to any suggestions along these lines.
 

·
Registered
'93 SedanDeville 60 Special
Joined
·
730 Posts
Here is an example of what you should see if your scanner supports the PIDs
This was in testing a 2014 Corvette I was working on a few day ago

Notice how the PCM to the DI controller commands the amount of fuel pressure as RPM and MPH called for

In this case 55 to 85 PSI at fuel rail

598396
 

·
Registered
'93 SedanDeville 60 Special
Joined
·
730 Posts
I just ordered the bluetooth OBD2, and some others in this forum suggested the Torque app for android to connect to it. I don't know if the app has those parameters or not, but I'm open to any suggestions along these lines.
I would be surprised that a cheap OBD scanner would fully support all GM enhanced PIDs
Maybe download their software and see what PIDs they have as you get what you pay for

Mine is a professional scanner, cost - $2,500 :(
 

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #17 ·
Here is an example of what you should see if your scanner supports the PIDs
This was in testing a 2014 Corvette I was working on a few day ago

Notice how the PCM to the DI controller commands the amount of fuel pressure as RPM and MPH called for

In this case 55 to 85 PSI at fuel rail

View attachment 598396
Interesting results. I would not have expected such a high pressure at idle, then the pressure bouncing between high and low like that during acceleration. Guess it makes sense as the pressure builds with RPMs and the individual injectors open and stay open longer when more power is needed, dropping the pressure. Also interesting to see the pressure build linearly as the throttle is obviously closed.
But yeah, I only work on my own vehicles, so it would be hard to justify the $2500, although it would be very nice.
 

·
Registered
'93 SedanDeville 60 Special
Joined
·
730 Posts
With the addition of DOD/AFM, DI and variable timing the fuel systems have gotten very complex in how they work
At time an injector has to look like 30 lb/hr and as high as 120 lb/hr.

Add where the driver if design supports it can set engine modes, like cruising to sport, to track modes the controllers adjust for that

Finding a decent OBD scanner is a zoo as way too many cheap generic types are sold and people buy them as it might look cute on their cellphone to having no clue what a scanner should do and of course low costs

Maybe do a internet search for OBD-II scanner that state they support GM "enhanced" and up to recent model year GM vehicles.
 

·
Registered
Joined
·
71 Posts
I had similar issue with my car and it was bad injectors. What sucks is you will want to replace both of the high pressure fuel lines coming off the hpfp and that pressure sensor again. I bought all new injectors and replaced them but it was not an easy job or at least it wasn't for me. Plan on getting the old injectors cleaned and keeping them. Oh I also went ahead and bought a new manifold gasket which was not required. Good luck, hope you get it figured out. As soon as I got mine fixed I got the bad tone ring no abs, no traction control, no stabiltrak, no all wheel drive code again. So I guess I have another weekend replacing some hubs. I still love my car though.
 

·
Registered
2007 CTS 3.6 RWD Black 2008 CTS 3.6 DI RWD Red
Joined
·
58 Posts
Discussion Starter · #20 ·
I had similar issue with my car and it was bad injectors. What sucks is you will want to replace both of the high pressure fuel lines coming off the hpfp and that pressure sensor again. I bought all new injectors and replaced them but it was not an easy job or at least it wasn't for me. Plan on getting the old injectors cleaned and keeping them. Oh I also went ahead and bought a new manifold gasket which was not required. Good luck, hope you get it figured out. As soon as I got mine fixed I got the bad tone ring no abs, no traction control, no stabiltrak, no all wheel drive code again. So I guess I have another weekend replacing some hubs. I still love my car though.
Did you have the "low fuel rail pressure" P0087? And did the injectors solve that problem? Did it take it out of limp mode? So if so, is the stabilitrak, abs, and all a separate issue?
 
1 - 20 of 50 Posts
Top