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Discussion Starter #1
So I have a 2008 Cadillac cts4 3.6l di awd. My vehicle has roughly 159,000 miles. I have been noticing some issues with a rough idle. At speeds around 45 to 50 is when it often starts. The vehicle becomes jerky, wants to die, has poor acceleration and smoke coming from the exhaust intermittently.

I thought it might be my ignition coils so I replaced all six ignition coils and spark plugs. I noticed some oil while replacing the plugs but because my oil pressure and oil level are not ever low I figured I would worry about the intake and cylinder gaskets later.

After replacing car ran smooth for about a week and has started doing it again. I have heard two different sides on the cleaning of di fuel injectors. Cleaned throttle body and maf sensor. Also used used bbk in my gas. Only get premium fuel.

Codes:
P0300 random misfire
P0302 misfire cylinder 2 P0089 FPR performance
P0154 02 circuit no activity detected bank 2 sensor 1
P0304 misfire cylinder 4

Have had other codes similar issues prior to replacing coils and plugs but the FPR code is new.

Please any help would be appreciated.
 

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08 CTS DI
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That P0089 is the most important on the list, it can cause all the others. Puffs of smoke and misfires, that tend to get worse with speed, sounds like the fuel pump can't keep up with fuel demand and is causing erratic changes in fuel pressure making it difficult for the computer to maintain consistent control.

You need to have the fuel pressure checked for both pumps although it is likely the high pressure pump that is causing the problem.
 

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'12 CTS Performance Sports Wagon AWD
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If you have an issue with that HPFP it is a pain to change so it will be expensive. I would suggest not taking to a dealer unless you absolutely half to. Could easily be a $1500 bill from a dealer to change a pump you can pick up for $100 elsewhere. I am changing the one in mine now although my engine is a little different.
 

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Discussion Starter #4
If you have an issue with that HPFP it is a pain to change so it will be expensive. I would suggest not taking to a dealer unless you absolutely half to. Could easily be a $1500 bill from a dealer to change a pump you can pick up for $100 elsewhere. I am changing the one in mine now although my engine is a little different.
Yea after looking into it some more the ac delco pump is $317 and that's with my discount. I am planning on changing it myself although from what I have heard the crank shaft has to be turned to low position in order to put the new high pressure fuel pump on but it is right on the top backside of my engine. Any helpful tips from anyone before I start the process would be great.
 

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Discussion Starter #5
That P0089 is the most important on the list, it can cause all the others. Puffs of smoke and misfires, that tend to get worse with speed, sounds like the fuel pump can't keep up with fuel demand and is causing erratic changes in fuel pressure making it difficult for the computer to maintain consistent control.

You need to have the fuel pressure checked for both pumps although it is likely the high pressure pump that is causing the problem.
I have a question I was also thinking high pressure fuel pump because it seems to me it is being flooded with fuel which is burning off in the catalytic converter. Is there a way for me to test the fuel pumps myself?
 

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If you have a tech2 they have some tests you can do.

Your car is doing stuff similar to mine although worse. My 2012 has 110k miles on it and was only throwing a code for fuel rail pressure performance. After changing the fuel pressure sensor I decided to switch the HPFP. This became a pain because my big hands so I took off the fuel rails to make it like 99% easier. This requires you to rebuild the injectors. I sent them off to be flow tested for $25 apiece but takes about a week to send them out and get them back. In my case the guy said all 6 were having issues flowing properly. After cleaning them 5 of them were back to new condition but one was sticking still and needs to be replaced.

Dealer pricing for this injector is $130, Local autozone for who knows what brand, for $110, Napa and ACI both have to order them in but have them available.

In my case my car had rough idle and occasionally threw codes at low rpms. May have also had a gas smell but did not notice it.

Also, my car has an LFX and yours has the LLT. Slightly different engines.

You can get a tech2 clone for about $300-$400. With it I was able to do an injector test which showed the injectors to be suspect as they were not all flowing the same. I was also able to test the fuel pumps. The in tank one was fine, the HPFP was dropping to 38PSI at idle and jumping around from 38 to 100psi. Minimum is supposed to be 500psi. But it only did this once you reved it up to over 2000psi first. Just never got back down in pressure.

In my car I was having a heck of a time with the HPFP because of my big hands so I pulled the fuel rails for better clearance which meant the injectors needed to be replaced or cleaned. I had "Doctor Injector" do mine. He told me all 6 were not flowing right when he initially tested them. After cleaning then testing them 1 injector was still bad and the other 5 are flowing like new. I will be replacing that 1 injector. I would not have known this if I had not sent them out and had them tested/cleaned/rebuilt.

I would suggest with your symptoms before changing out the HPFP to have your injectors cleaned and inspected. If you go through someone like the guy I did he can tell you if the injectors are bad. He didn't charge me for the bad injector. Only the ones he was able to bring back. If your injectors are not bad I would then replace the HPFP. If they tested bad before they clean them but they are good afterwards then I would reinstall them and see how it goes. Might be the issue with your car.

If you can otherwise have a trusted non-dealer mechanic atleast diagnose your car it may save you a lot of headache.

The tech2 does show the fuel pressure of both fuel pumps and allows you to raise the pressure on the HPFP to see if it can go up and down. In my car I suspect I had a bad HPFP and injectors. We will find out when I put it back together when I get the injectors tomorrow.

If you replace the HPFP I would do it with the fuel rails out but you may be able to do it with the LLT if you have smaller hands. I wear a 2XL glove and it wasn't happening for me.
 

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I have a question I was also thinking high pressure fuel pump because it seems to me it is being flooded with fuel which is burning off in the catalytic converter. Is there a way for me to test the fuel pumps myself?
Stop driving it for sure to avoid damaging it and burning up your converters. A good scan tool that can read both, or at least the fuel rail pressure which should be around 500 psi +/- ~50 psi should give you some insight. You can get an A/C Delco pump for under $200 from Rockauto, search out a 5% off coupon to cover shipping.

Since you have an 08 like me your pump replacement will not be as difficult as redheadedrod's. You also have different injectors than he does also, so you should be fine starting with the fuel pump first. It is also required that you replace the pressure sensor on the fuel rail if you remove it, although some may not and any of the two fuel pipes once removed.

I have a thread on the forum somewhere on how to replace the pump that should be perfect for you if you can find it. At 159k miles, I don't think you're wrong at all for looking at the pump. I replaced mine around 176k miles as preventive maintenance.

The Tech2 clone would be awesome if you had it, but you need something cheap and effective now so search out the cheapest tool you can find that will read the rail pressure. You can check the in tank pump pressure at the check valve on the back side of the motor; 55-60 psi ignition on, engine off. Mine was around 51 psi because of a small elbow leak but it did not affect fuel delivery and did not set any code because of it.
 

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Still strongly would suggest getting the injectors cleaned first... You may still end up needing to replace the HPFP but if yours at 170k are anything like mine are at 100k you need them cleaned anyhow. Or replace them.. .Either way.
 

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Discussion Starter #9
Okay one more question. When buying the HPFP one person said Delphi was OE and another said Delco, which one is it? My 8th letter of my vin is a V. Also is the AC Delco from the dealership better than the one at Autozone?
 

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Delphi is contracted to make parts for GM.
 

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Dealer just costs more... Many different places have the same pump. I just bought one for my car for $120 at Napa. I think it was $170 but I have a Gov't Employee discount. They had another unit for $500... No explanation on it. You can also take the GM part number and do a search and find places selling it for much cheaper too. AcDelco is Ac Delco.. The Dealer normally puts a ~100% cost over wholesale pricing. Most other outlets charge far less than that. If you have a mechanic friend you can also get the "Jobber" discount which is what I am getting being a gov't employee.
 

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to further add to the confusion, many parts marked AC Delco Professional are actually made by other than AC Delco manufacturers but should meet the Original Equipment Manufacturer specifications...if looking on RockAuto or other sites (and be sure to look on this Forum for the constant 5% discount code) you sometimes will see one part is the actual OEM part and you may see a red heart after the part which just means it is a popular choice...

check their Forum for parts used with success (and sometimes those purchased that caused tears later ;) )...

Good luck with your choice,

Bill
 
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