2005 H2 Knock sensor nightmare. Please help!
#1
12-01-2018, 09:02 PM
2005 H2 Knock sensor nightmare. SOLVED!!!
Hello guys,
I wrote a post about cheap knock sensors a while back and following other members advise I’ve finally replaced them with AC DELCO ones.
This is what my mechanic has done so far after getting a knock sensor on bank 2 code:
- Replaced the cheap Chinese ones with a pair of supposedly good ones readily available on the local market (Panama) and replaced the wiring with new oem cables.
They solved the lack of power and hesitation issues for about a few hours and then back to square one.
- A couple of days ago, I got the AC DELCO sensors, removed the intake, cleaned everything up, changed the sensors and put silicone around the rubber seals. The only thing I did not do was to replace the gasket seals.
The H2 came back to life with all its glorious power!... for only about 10 miles!!!!
As as soon as I was getting on the highway, the engine started hesitating again and lost 80% of its acceleration and power.
I don’t know what else to do!! My scanner now gives both banks 1 and 2 error messages.
I am about to measure the ohms on the connector to make sure the reading is correct but, other than that I feel completely hopeless.
Is it possible that something else could be the cause for knock sensor failure? Or, If the sensors are indeed working properly and the wiring is good, what else could be fooling the ecu into thinking they are not?
If this was the case, could engine hesitation and lack of power be the cause and perhaps not the symptom of knock sensor DTC errors?
Thank you in advance for any help in this matter.
I wrote a post about cheap knock sensors a while back and following other members advise I’ve finally replaced them with AC DELCO ones.
This is what my mechanic has done so far after getting a knock sensor on bank 2 code:
- Replaced the cheap Chinese ones with a pair of supposedly good ones readily available on the local market (Panama) and replaced the wiring with new oem cables.
They solved the lack of power and hesitation issues for about a few hours and then back to square one.
- A couple of days ago, I got the AC DELCO sensors, removed the intake, cleaned everything up, changed the sensors and put silicone around the rubber seals. The only thing I did not do was to replace the gasket seals.
The H2 came back to life with all its glorious power!... for only about 10 miles!!!!
As as soon as I was getting on the highway, the engine started hesitating again and lost 80% of its acceleration and power.
I don’t know what else to do!! My scanner now gives both banks 1 and 2 error messages.
I am about to measure the ohms on the connector to make sure the reading is correct but, other than that I feel completely hopeless.
Is it possible that something else could be the cause for knock sensor failure? Or, If the sensors are indeed working properly and the wiring is good, what else could be fooling the ecu into thinking they are not?
If this was the case, could engine hesitation and lack of power be the cause and perhaps not the symptom of knock sensor DTC errors?
Thank you in advance for any help in this matter.
Last edited by Hbrezzi; 06-07-2019 at 09:24 PM. Reason: Update
#2
12-02-2018, 08:02 AM
Was the old code cleared ? If not it might come back up. Are there any other codes?
Generally the knock sensors indicate another problem, they do not cause it. Check fuel, plugs and coils and the MAF. I would then look at the tune and see if anyone has messed with it.
Also check the exhaust manifolds to make sure they are not loose and or rattling on the heads. The sensors are dumb, they can not recognize detonation from a piece of metal hitting something.
tim
Generally the knock sensors indicate another problem, they do not cause it. Check fuel, plugs and coils and the MAF. I would then look at the tune and see if anyone has messed with it.
Also check the exhaust manifolds to make sure they are not loose and or rattling on the heads. The sensors are dumb, they can not recognize detonation from a piece of metal hitting something.
tim
#3
12-02-2018, 12:27 PM
Hello Tharber,
yes the codes were cleared. New MAF (oem), new coils, new plugs.
I don’t really know how to go about checking the tune. Any tips?
Interesting point you make about the exhaust manifolds and I’ll definitely look into it.
Thank you for your input!
Hans
yes the codes were cleared. New MAF (oem), new coils, new plugs.
I don’t really know how to go about checking the tune. Any tips?
Interesting point you make about the exhaust manifolds and I’ll definitely look into it.
Thank you for your input!
Hans
#4
12-02-2018, 12:50 PM
Could also be a leak on the intake somewhere, clogged cats, clogged fuel filter (only 2003 has a replaceable fuel filter, other years it is part of the fuel pump), or a fuel pressure issue like maybe the pump works fine until it gets hot or the fuel pressure regulator starts flaking out once hot or something, crank or cam position sensors getting flaky. This is one of those unfortunate issues where there is no simple and definitive obvious culprit and the only way to proceed is to start going after potential culprits one at a time in a process of elimination. 
#6
12-04-2018, 08:58 PM
need to monitor cyl #1 timing and knock retard to see whats going on.
you can do it fairly cheap, an obd II adapter on ebay and the torque pro app on your phone should do it, wifi for iphone or Bluetooth for android
I'll have to make sure Torque will do knock,
Neal
you can do it fairly cheap, an obd II adapter on ebay and the torque pro app on your phone should do it, wifi for iphone or Bluetooth for android
I'll have to make sure Torque will do knock,
Neal
#7
12-05-2018, 09:01 AM
Torque does not read timing. It can however clear fault codes and other than the OBDII reader, its free.
To see the timing and A/F ratios you will need to have a Tech 2 programmer or something like HP Tuners.
Cylinder #1 is not the key. The knock sensors just indicate any type of knock and they are not specific. As I stated before, any type of metal on metal knock can and will trigger the sensors. It could be loose manifold bolts, loose transmission, loose accessories, etc. it doesn't take much.
Tim
To see the timing and A/F ratios you will need to have a Tech 2 programmer or something like HP Tuners.
Cylinder #1 is not the key. The knock sensors just indicate any type of knock and they are not specific. As I stated before, any type of metal on metal knock can and will trigger the sensors. It could be loose manifold bolts, loose transmission, loose accessories, etc. it doesn't take much.
Tim
#8
12-05-2018, 07:44 PM
I've been using torque Pro for years now and mine does read timing along with many other sensors. The one in question is knock, i'll have to check and see if it does.
Identifying when the knock is being picked up by the ECM is critical to troubleshooting the issue, if its tied to a timing event you'll see it while monitoring both sensors.
Torque has a data logging add on now that can come in handy,
I've got a few scanners and usually start with torque or dash command then if bi-directional control is needed or I need to see ABS or air bag PID's I'll use one of the others just depends how in depth I need to get (TechII, ScanXL, Ease diagnostics).
Neal
Identifying when the knock is being picked up by the ECM is critical to troubleshooting the issue, if its tied to a timing event you'll see it while monitoring both sensors.
Torque has a data logging add on now that can come in handy,
I've got a few scanners and usually start with torque or dash command then if bi-directional control is needed or I need to see ABS or air bag PID's I'll use one of the others just depends how in depth I need to get (TechII, ScanXL, Ease diagnostics).
Neal
#10
12-13-2018, 08:50 PM
Thank you all for your precious input.
As as I mentioned, I have replaced the non oem knock sensors with oem ones and no luck... a few miles later still the same power issues and knock sensors codes (both banks).
Strangely enough, both times I replaced the sensors, the Hummer starts driving great with all of its original power but, as I said, a few miles later I’m back to square one :-(
Yesterday, I took the injectors and rails to a specialized shop and $180 later they told me they were finally as good as new. 4 where very dirty, 2 completely clogged, and 2 were injecting too much fuel... So they said...
My mechanic friend took down the gas tank and “cleaned” the pump filters. After bleeding the lines, fuel color changed from tar to clear. I was indeed happy to see that!.
After putting everything back together, the H2 felt idling much better. Cleared the codes and took it for a spin. Some hesitation was still noticeable and engine power felt at 80%. Not too bad all things considered...
Today, I drove it for 100 miles and, after only 30 miles, it lost again most of its power. There is also a very strong gas smell that comes from the back (not from the engine).
When I kicked it down (downshift), the car accelerated, with hesitation, but enough to pass other vehicles. If I didn’t downshift and only apply pressure to the gas pedal, it just didn’t accelerate and felt as if it got “flooded”.
Curiously, the engine seemed to be less hesitant at or above 60mph. 3000+ rpms?
Tomorrow, my friend will check where the fuel smell comes from and, as advised, check for anything loose that may be knocking on the engine.
I will try to have him monitor with the scanner engine data while driving.
I will let you all know how it goes and I thank you again for your support!
Hans
As as I mentioned, I have replaced the non oem knock sensors with oem ones and no luck... a few miles later still the same power issues and knock sensors codes (both banks).
Strangely enough, both times I replaced the sensors, the Hummer starts driving great with all of its original power but, as I said, a few miles later I’m back to square one :-(
Yesterday, I took the injectors and rails to a specialized shop and $180 later they told me they were finally as good as new. 4 where very dirty, 2 completely clogged, and 2 were injecting too much fuel... So they said...
My mechanic friend took down the gas tank and “cleaned” the pump filters. After bleeding the lines, fuel color changed from tar to clear. I was indeed happy to see that!.
After putting everything back together, the H2 felt idling much better. Cleared the codes and took it for a spin. Some hesitation was still noticeable and engine power felt at 80%. Not too bad all things considered...
Today, I drove it for 100 miles and, after only 30 miles, it lost again most of its power. There is also a very strong gas smell that comes from the back (not from the engine).
When I kicked it down (downshift), the car accelerated, with hesitation, but enough to pass other vehicles. If I didn’t downshift and only apply pressure to the gas pedal, it just didn’t accelerate and felt as if it got “flooded”.
Curiously, the engine seemed to be less hesitant at or above 60mph. 3000+ rpms?
Tomorrow, my friend will check where the fuel smell comes from and, as advised, check for anything loose that may be knocking on the engine.
I will try to have him monitor with the scanner engine data while driving.
I will let you all know how it goes and I thank you again for your support!
Hans