Kazza

Today I changed the fuel filter, spark plugs and I also pulled and cleaned the drivers side upstream (precat) o2 sensor (couldn't get to the passenger side) and cleaned the throttle body butterfly valve. I also checked all 4 corners and wheels all spin without much effort. Car also coasts in neutral no problem. I'm still experience this issue of the truck generally hesitating to go into a higher gear/driving at higher revs. I've also got a ses light since doing the work today.. don't have a code reader will see if it dissapears after a few drives. I'm thinking perhaps this is transmission related. I have never changed the fluid on it and it'd 170kms.. is it advisable? I've heard mixed stories about changing fluid on a tranny that's higher mileage

Hi guys, Bit of an odd one but recently I have noticed my QX4 seems to be struggling a bit. I find the auto transmission is always in a higher gear than normal when accelerating. It still cruises at highway around 2k rpm but it will drop a gear at the slightest gradient (even flat ground sometimes) when I apply even light acceleration, and too easily drops 2 gears and starts screaming above 3k rpm sometimes when it just really shouldn't be. I noticed this change around the same time my muffler broke away from the midpipe and my fuel lines took some serious heat from the exhaust fumes (even melted the carpet in the trunk) for a few days before I bandaided it back together. I was just running with the problem for a few weeks but yesterday my car almost overheated for the first time climbing a hill.. and now I'm faced with both issues and can't ignore it. Could the exhaust heat have kinked my fuel lines and affecting fuel delivery/pressure? I'm a bit at a loss as to what else could have caused this, no codes throwing. All maintenance done (apart from spark plugs slightly overdue).

@Slartibartfast My plan was to go back to the shop that done road force and ask them if they could look at the results again and tell me if it's possible I have a tire/wheel defect.

Update: had the road force done today, they rebalanced all 4 tires (3rd time now), the wobble is better but not gone. It's now wobbling in a smaller range ~75 to ~100km/h. I haven't called them back but they didn't mention anything about issues with the wheels/tires. I'm a bit at a loss right now, I think I'm going to put the oem rims/with my old tires back on and drive it to check the difference again for my own sanity. I'm sure i had zero wobble before. I didn't get a print out or anything from the road force balance, they just gave me a receipt for the work. Not sure on next steps really. Paid for an alignment and 2x balance now (2 different shops). I don't really want to just live with it because the tires are new and were expensive. I'm expecting a smooth ride.

@The_Oregonian the suspension parts you mentioned are all new - didn't have the wobble after replacing suspension parts and still running my old summer alloy/wheel combo. The steel wheels are old though, from an old chevy. Not signs of impact damage, rim beads all looked nice and round when I resprayed them. The tire shop with road force said they could check if a rim is damaged though when they are doing the balance tomorrow. @Slartibartfast hub rings fill the gap between the hub and the wheel bore, they are the right size for the job so wheels should all be centered properly on the hubs. No wheel weights had fallen off, I checked them all before going back to the shop. All wheels got rebalanced on the 2nd attempt anyway so kinda rules that one out. The only things I've not changed on the front are the control arms or the rack bushings.. so this could be the issue. Again strange if it is suspension related because, as I mentioned earlier, my old summer wheel/tire combo didn't have the wobble. The extra weight of running wider steelies with bigger/wider tires could be a highlighting a problem with these bushings though. I guess I will see what comes out of the road force balance tomorrow. The new shop are telling me they will be able to diagnose if it's a bad tire, improper tire mounting or a bad wheel. Thnx for input so far, will report back soon.

Hi guys, I put 15" steel rims on my 2001 QX4, with 31" tires.. The rims are Chevy lug centric, so I also installed the proper acorn style lug nuts and bought 100 to 108mm hub rings to close the gap between hub and rim. I gave the rims to the local tire shop to mount and balance brand new Falken Wildpeak AT3W's but I had a steering wobble straight off the bat at highway speeds 80km+. Previous to installing the new wheel/tire combo, I had just redone my full front end - repack hubs, shocks, springs, ball joints etc, and had an alignment done with my old summer tires and I had no steering wobble. Therefore, I was/am confident i can isolate the wobble to the new wheels/tires. I've just got the car back off the shop again, they found that all 4 wheels were out of balance (even though they balanced them before) and so all new wheel weights put on. Ive just taken it for a test drive and I still have the same steering wobble. It was a different guy who balanced the wheels this time and he told me that the tires are too big and that it will be difficult/impossible to have a smooth ride on them regardless if balanced or not. Looking for opinions on next steps here.. is it worth my while going to a shop that specializes in tires/balancing or is the guy at the shop right and I need to live with this inconvenience? Thanks in advance for input. EDIT: I should add, I've booked in to a different shop in town next week who have the Road Force system, I believe they are the only shop that have this machine so hopefully they can either sort the issue or give me a better explanation of what the problem is.

Apologies I forgot to tie this one up.. I removed the Mode Door Motor (located on right side of driver footwell) and found that the metal rod that is attached was sticking in the track. I just sprayed it with some.lubricant and it's worked fine ever since.

Thnx will give them a ring!

Can anyone help me look up the paint code for a QX4 if I pm them the VIN? I can't physically look at the vehicle at the moment but need to confirm a paint match. Thnx!

Got an update on this.. Done some checks on the wiring between the A/C Auto Amp and the Mode Door Motor. I'm getting ~12v on the power wire to the motor which mean its getting enough power, continuity on the ground wire, but I'm only getting ~2v on the signal wire and it says i should be getting ~5v. I have not checked the Air Mix Door but they share the same signal wire from the A/C Auto Amp.. so it currently looks like the A/C Auto Amp is the problem. This diagnosis makes more sense since both doors seem to have stopped working at the same time.

Hi guys, just tonight realized that neither the "Mode" Door (directs air between feet/body/defrost) or "Air Mix" Door (controls air temperature) work on my HVAC. I'm getting hot air only and its only coming from the defrost vent. I have ran the HVAC self diagnostics as per the FSM and I'm getting the following error codes: Sensor error #26 - Air Mix Door Motor (LCU) PBR Door Motor Switch errors ~31, 32, 34, 35, 36 I have checked the connectors into both the air mix door motor and mode door motor, both are plugged in. This is as far as I have went tonight, but it seems I have one of the following; 1. An electrical issue before both door motors (A/C Auto amp or harness) 2. Both motors have somehow failed at the same time. 3. Both doors/motors are frozen due to the recent sustained sub zero temperatures where I live. Another thing is.. I just got the car back from having my windshield replaced (leaking windshield due to rust where the roof meets the windshield) and this is the first i've noticed the issue. I've been looking at the wiring harness locations to see if this could possibly have been caused by the mechanic changing the windshield. I know the main harness is somewhere near where the windshield meets the firewall area but can only really speculate. Any thoughts?

Starbai did you get this sorted?

What rims are those you are rockin @PATHYNDH?

I've recently put OME springs on the rear of the truck and am awaiting some sfcreations 1.5" spacers + camber bolts to level her out. The plan is to install the spacers and camber bolts then take for alignment. After calling around the mechanics I found one which will do the alignment including camber adjustment and said this would typically take 1 to 1.5hrs. They, and the other mechanics I called, did warn me however that it could easily turn into a 4 or 5 hour+ job if they run into any seized bolts. So in an effort to save this alignment becoming a costly job I'm hoping to identify each and every bolt that could potentially need undoing to do an alignment on the R50 suspension so I can loosen/retighten in advance. Can anyone chime in on this and help me identify what needs done? Thanks, K

I'd get the tires you want.. throw them on and then see what issues arise from driving it and act from there.