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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet camaro: 2010 camaro v6. went into limp mode, multiple

Customer Question

2010 camaro v6. went into limp mode, multiple codes, including misfire, o2 sensors and more importantly p0087 and p0091. Checked fuel pressure on high pressure pump, was too low. Checked pressure on low pressure pump, was fine. replaced high pressure fuel pump. still had problems, replaced fuel pressure sensor, still have problems. rechecked low pressure fuel pump, pressure was too low, bad pump. replaced that pump as well, car still stuck in limp mode and the car still showing p0087, p0091 and misfire codes. Tired of replacing thing and not getting anywhere. Car has a history of cheap gs, and waiting till the light comes on to refuel.
Submitted: 2 years ago.
Category: Chevy
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  GM Tech (Cam) replied 2 years ago.
Hello, I'm Cam.
Can I get your first name please?
Sorry to hear about this issue. I'm guessing that clearing the coach does not keep them off?
Currently what do you have for your measured low pressure pump pressure and are you testing with a manual gauge or with the sensor?
Customer: replied 2 years ago.
Nohl is my name.
Clearing the codes does nothing
The car is still at the shop currently after the lower pressure fuel pump replacement, so i don't know the current fuel pressure levels. but the high pressure pump was fluctuating all over the place.
the low pressure pump (before replacement) was around 25psi, even when keyed to ignition on, the pump would not retain the 55 psi it should to prime the system, the psi would rapidly drop to 25 psi and just sit there.
Customer: replied 2 years ago.
after i replaced the high end pump, its pressure was up but not near correct operating pressure and still fluctuating. Same issue persisted after fuel pressure replacement as well.
Customer: replied 2 years ago.
Currently both pumps (high and low pressure) and the fuel pressure sensor have all been replaced with AC delco units and the car is still in limp mode.
Expert:  GM Tech (Cam) replied 2 years ago.
Sorry Nohl, my wife tagged me for supper. What is the current high pressure reading then? IT should be between 508 and 798 psi. Is it there?
Customer: replied 2 years ago.
between 380 and 575, but not stable.
Expert:  GM Tech (Cam) replied 2 years ago.
Does your scanner allow you to control the pressure?
Customer: replied 2 years ago.
no
Expert:  GM Tech (Cam) replied 2 years ago.
Ok, do you have the diagnostics for that code?
Customer: replied 2 years ago.
i looked up the codes yes. p0087, p0091, p0088. p0275, po276, p0274, p0273.
Expert:  GM Tech (Cam) replied 2 years ago.
ok so we may have 2 issues happening at once. What circuit testing have you done for the fuel pumps? How about for the P0273-275?
Customer: replied 2 years ago.
none. the misfire codes were assumed to be a byproduct of the bad fuel pressure from the pumps.
Customer: replied 2 years ago.
sorry I was looking at the wrong notes. those should of been p0304, p0303, p0305, p0306.
Expert:  GM Tech (Cam) replied 2 years ago.
Ok, those are misfire codes, and could be related to the other codes. Lets step back a moment, exactly what codes are set? P0087, P0088? P0091?
Customer: replied 2 years ago.
I had been troubleshooting the problem and trying to single things out. i knew that if it stayed p0300 codes it was a misfire, where if the po275 codes came up it would be something different. anyway. i assumed the p0300 codes were a result of the bad fuel pressure. a friend who is a GM dealer mechanic (he does not have as much experience as you) confirmed to me that the misfires were a product of the bad pumps and I should fix the pumps and fuel pressure and once that was fixed the misfires would go away.
Customer: replied 2 years ago.
Current codes - p0087, p0089, p0091, p0300, p0303, p0304, p0305, p0306. There were more but they cleared with the installation of new parts.
Expert:  GM Tech (Cam) replied 2 years ago.
OK, so we need to diagnose the lowest code, in this case the P0087, fuel pressure.
Here is the GM diagnosis for that code, copy the link to your browser.
https://dl.dropboxusercontent.com/u/22552935/p0087.pdf
Customer: replied 2 years ago.
I have seen this before. looked it up online when the codes originally hit. fuel pressure fluctuates which triggered all three codes. 087, 088, 089
Customer: replied 2 years ago.
when turned on the car wont hold the required pressure to run the testing. inconsistent pressure from the get go. I checked the pressure at the rail for the low pressure pump (rail back to gas tank and pressure was fine). So I replaced the high pressure pump as it seemed to be the problem. After high pressure pump replacement the 02 sensor codes went away and fuel pressure was higher, but not consistent, still showing p087, p088, p089 and p0300 codes along with a new code, p0191, fuel pressure sensor circuit range performance. Found diagnostic online, recommended replacing unit, so I did. p0191 went away other codes remained.
Customer: replied 2 years ago.
at this time i rechecked the pressure on the low pressure fuel pump. At this point the low end fuel pump had inconsistent and weak fuel pressure. deduced that the pump must be bad, so I sent the car to the shop to replace the fuel pump as I don't have the time or a lift to do this repair (or i would have). currently the car idles better, does not stall and die but the misfire and fuel pressure codes still exist. car is still in limp mode.
Expert:  GM Tech (Cam) replied 2 years ago.
Ok, so that may still in fact be our issue or help lead to the issue. Having a new pump both high and low pressure suggests there may be a problem with a sensors and the P0087 and such do not address that. I know you said the P0191 went away, I would like you to follow through the testing for that code anyway to ensure its not a wiring issue. Below is the test from there.
Ignition OFF, disconnect the multi-way harness connector X161 at the rear of the intake manifold.
2. Remove the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.
Note: Testing for steps 3 through 7 is performed on the ECM side of the multi-way harness connector.
3. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 5 and ground.
⇒ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
4. Install the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.
5. Ignition ON, test for 4.8–5.2 V between the 5-volt reference circuit terminal 11 and ground.
⇒ If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
⇒ If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
6. Ignition ON, verify the scan tool FRP sensor voltage parameter is greater than 4.96 V.
⇒ If less than the specified value, test the signal circuit terminal 12 for a short to ground. If the circuit tests normal, replace the ECM.
7. Connect a 3 A fused jumper wire between the signal circuit terminal 12 and the low reference circuit terminal 5. Verify the scan tool FRP voltage parameter transitions from greater than 4.96 V to less than 0.02 V.
⇒ If the parameter does not transition from the maximum to minimum value, test the signal circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the K20 ECM.
8. Ignition OFF, remove the intake manifold.
9. Connect the multi-way harness connector X161.
Note: Testing for steps 12 through 16 are performed at the FRP sensor connector.
10. Disconnect the B47 FRP sensor connector.
11. Remove the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.
12. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 1 and ground.
⇒ If greater than the specified range, test the low reference circuit for an open/high resistance.
13. Install the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.
14. Ignition ON, test for 4.8–5.2 V between the 5-volt reference circuit terminal 3 and ground.
⇒ If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance.
⇒ If greater than the specified range, test the 5-volt reference circuit for a short to voltage.
15. Ignition ON, verify the scan tool FRP sensor voltage parameter is greater than 4.96 V.
⇒ If less than the specified value, test the signal circuit terminal 2 for a short to ground.
16. Connect a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the scan tool FRP voltage parameter transitions from greater than 4.96 V to less than 0.02 V.
⇒ If the parameter does not transition from the maximum to the minimum value, test the signal circuit for an open/high resistance or a short to voltage.
17. If all circuits test normal, replace the B47 FRP sensor.
Customer: replied 2 years ago.
So we checking to see if its the sensor or the actual ecm? Great. Just for kicks if it manages to pass both of these tests, what is left?
Expert:  GM Tech (Cam) replied 2 years ago.
Don't forget the wiring. A bad connectoin, chaffed wire and such will cause this. In the diagnostics they remind the techs to zero the meter leads to ensure an accurate reading. SO the sensor,, ECM or wiring could be faulty. It may be that the sensor wiring had a bad connection, varies the reading back to the ECM, but its still with out specs. then the ECM does not realize the sensor reading is not accurate for the actual reading and commands the fuel according to what it thinks the issue is.
Customer: replied 2 years ago.
i will have the shop check this. If this comes back clean, than whats left? The actual fuel pump module or the ecm?
Customer: replied 2 years ago.
i have not been throwing any codes to point to a leaky injector but could that be a culprit either?
Expert:  GM Tech (Cam) replied 2 years ago.
Its possible. Lets follow through the diagnosis for the 191 that I posted and then see about the 0087. Lets not jump around or we may loose track. Its best to stick with one course and follow it through.