Topic: Z22XE hesitates at full throttle (Read 4866 times)

Opelduude · « **on:** 07 July 2019, 20:03:10 »

I have ignored this for a long time but its soon 3 weeks of vacation and time to give some love to the car.
Some days the car hesitates at full throttle and the next day it's all fine. Very annoying because i'm towing a trailer a lot during the summer and need all the power it should have.

No fault codes. I have limited access to live data. I suspect that the o2 sensors are becoming slow to regulate. There is also no difference when i unplug the maf. No engine light and it still runs smooth at idle.

The coil and spark plugs where new last autumn and the valve cover gasket this spring. No oil on the plugs when i checked today. Cleaned the throttle body a couple of months ago too. Fuel filter and fuel pump was replaced just before i bought it.

Doctor Gollum · « **Reply #1 on:** 07 July 2019, 20:30:50 »

Sounds like a sticky throttle plate, but... When was the fuel filter last changed?

Also the thinner of the two breather hoses turns to a gooey mess. If it has the consistency of blutac, then change it and report back

Opelduude · « **Reply #2 on:** 07 July 2019, 21:04:49 »

The two breather hoses are new because the previous owner could not figure out why the car was erratic. I replaced the coil right after i bought it and solved it. As mentioned he also replaced the fuel pump and the filter right before i bought it.

Doctor Gollum · « **Reply #3 on:** 07 July 2019, 21:10:44 »

Quote from: Opelduude on 07 July 2019, 21:04:49

The two breather hoses are new because the previous owner could not figure out why the car was erratic. I replaced the coil right after i bought it and solved it. As mentioned he also replaced the fuel pump and the filter right before i bought it.

Have you personally checked?

Opelduude · « **Reply #4 on:** 09 July 2019, 19:28:52 »

Yes i have checked both again now. They are not clogged.

Opelduude · « **Reply #5 on:** 28 July 2019, 12:18:18 »

I tried to replace the maf just for the sake of trying something not so expensive.
No difference at all. I'm beginning to suspect that the throttle body are not working right. When it's cold it sticks at 1500 rpm which i guess is normal when the engine is cold. This "cold start" function lasts much shorter during the hot time of the year.
Since the car runs smoothly and there is no sign of jerking or jumping at full throttle if you understand. It seems like the car only thinks i'm only doing half throttle. Throttle body costs 350 pounds with discount so i don't want to buy that just to try it.
In case does the new one have to be programmed or adapted to the car?

Doctor Gollum · « **Reply #6 on:** 28 July 2019, 15:37:36 »

Nah, simply bolt it on, plug it in and fire it up

Opelduude · « **Reply #7 on:** 19 September 2019, 20:49:12 »

Going to replace the heater core this weekend.
Can't seem to find the guide for that on this forum anymore?

Enceladus · « **Reply #8 on:** 20 September 2019, 02:28:25 »

Look in the index page of the maintenance guides here. Scroll down and look for 'heater matrix'. There are two articles. One for remove'/replace and one for flushing/unblocking. I think they're for pre-facelift and your Z22XE must be a post facelift. Unless it's leaking into the cabin I would try and flush it before attempting to replace it. I'm still recovering from the last time I did that.

Last time I disconnected a MAF it triggered the fault light, so I don't get why yours doesn't.

Doctor Gollum · « **Reply #9 on:** 20 September 2019, 08:12:51 »

Cam sensor or crank sensor or belt timing slightly out.

None will stop it working, but each could cause high rpm hesitation.

When was the belt last changed and was the water pump done at the same time?

Opelduude · « **Reply #10 on:** 20 September 2019, 19:44:12 »

I'm not planning to pull the whole dash out.
The car is worth 1500 pounds at best so i will just cut in the interior.
The cam belt and all the other parts was changed this spring.

I have concluded that the throttle body is broken, haven't bought a new one yet because the car runs ok for now.

Doctor Gollum · « **Reply #11 on:** 20 September 2019, 22:02:04 »

Quote from: Opelduude on 20 September 2019, 19:44:12

I'm not planning to pull the whole dash out.
The car is worth 1500 pounds at best so i will just cut in the interior.
The cam belt and all the other parts was changed this spring.

I have concluded that the throttle body is broken, haven't bought a new one yet because the car runs ok for now.

Then the throttle body works...

Be worth checking the timing... Especially if the correct locking tools weren't used

Opelduude · « **Reply #12 on:** 20 September 2019, 22:09:52 »

Quote from: Doctor Gollum on 20 September 2019, 22:02:04

Quote from: Opelduude on 20 September 2019, 19:44:12
I'm not planning to pull the whole dash out.
The car is worth 1500 pounds at best so i will just cut in the interior.
The cam belt and all the other parts was changed this spring.

I have concluded that the throttle body is broken, haven't bought a new one yet because the car runs ok for now.
Then the throttle body works...

Be worth checking the timing... Especially if the correct locking tools weren't used

Seems more like the throttle body is too slow, the throttle sticks when cold.

I used a cam locking tool so the timing is perfect. I used to be a mechanic and these are one of the easiest engines to replace the belt on, so no need to be sloppy

Doctor Gollum · « **Reply #13 on:** 21 September 2019, 00:23:04 »

Quote from: Opelduude on 20 September 2019, 22:09:52

Quote from: Doctor Gollum on 20 September 2019, 22:02:04
Quote from: Opelduude on 20 September 2019, 19:44:12
I'm not planning to pull the whole dash out.
The car is worth 1500 pounds at best so i will just cut in the interior.
The cam belt and all the other parts was changed this spring.

I have concluded that the throttle body is broken, haven't bought a new one yet because the car runs ok for now.
Then the throttle body works...

Be worth checking the timing... Especially if the correct locking tools weren't used
Seems more like the throttle body is too slow, the throttle sticks when cold.

I used a cam locking tool so the timing is perfect. I used to be a mechanic and these are one of the easiest engines to replace the belt on, so no need to be sloppy

I hope you mean cam locking KIT along with a NEW water pump

Opelduude · « **Reply #14 on:** 21 September 2019, 09:20:41 »

Yes all the belonging parts to the cam belt was replaced of course. Tensioner, pulleys, water pump.

Opelduude · « **Reply #15 on:** 21 September 2019, 14:59:48 »

New heater matrix in place but now i'm struggling to get one of the quick connectors to lock. Useless plastic system.
The hose won't lock with the plastic clip in the outer or inner position.

Doctor Gollum · « **Reply #16 on:** 21 September 2019, 15:19:57 »

They take some force to remove/fit

Obviously make sure the seal and collar are correctly located

Nick W · « **Reply #17 on:** 23 September 2019, 13:45:24 »

Quote from: Doctor Gollum on 21 September 2019, 00:23:04

I hope you mean cam locking KIT along with a NEW water pump

the locking KIT for a 2.2 is just a wedge for the cams. Fewer pulleys and adjusters with only one belt run mean there's less to hold in position.

Opelduude · « **Reply #18 on:** 05 October 2019, 21:19:14 »

Replaced both of the o2 sensors today and gained at least 15 more horsepower. Seems like the car is good to go right now. See how long it lasts

Opelduude · « **Reply #19 on:** 06 October 2019, 15:46:30 »

It lasted until today when the engine warning light came on a gave me a P0420 code.
Catalyst System Efficiency Below Threshold...

Opelduude · « **Reply #20 on:** 02 May 2020, 09:24:30 »

I have found out that the content of the cat probably has been removed. Saw some welding marks on it that does not look original.
That explains why i get the fault codes.

The car has slowly started to become more sluggish again. Hesitates and sometimes even jerks a couple of times when i tow a trailer.

Enceladus · « **Reply #21 on:** 02 May 2020, 12:59:16 »

Try disconnecting the downstream lambda sensor and re-connecting. IE break and remake the connector. What make are the new sensors?

Or possibly the matrix in the downstream cat has fractured and is moving about. Thump it with the side of your clenched fist, make sure the cat is cold first. Listen carefully, can you hear the matrix rattling?

Where is the non-original welding? Ends of the flexi-joint? Or at the pre-cat?

Opelduude · « **Reply #22 on:** 03 May 2020, 16:43:19 »

The is a square welding mark on the center of the cat. Not professionally looking to say the least. There is only one cat on this as i can see?
No rattle noises at all.

The "new" sensors which i replaced last autumn was Denso and Bosch. Could only get one with the right connector so had to buy a universal one from Bosch. The wires are joined with proper cable lugs. The kind you melt at each end.

Enceladus · « **Reply #23 on:** 04 May 2020, 03:05:36 »

On the Z22XE the down-pipe from the manifold normally has two cats. A smaller pre-cat visible in the engine bay immediately downstream of the first lambda sensor. The larger main cat is further downstream just before the center silencer boxes.

If the car is Norwegian market maybe less onerous emission standards applied when new, but I would have thought it unlikely. More probable that the car was built like all the others to be Euro IV compliant.

So if you only have one cat in the down-pipe but two lambda sensors then somebody has cut out one of the cats, likely the upstream, and bridged the gap. Might it be that the square welding in the main cat is a patch to fix a hole? The other possibility is that somebody has fitted an earlier 2.0L down-pipe, but these have only one lambda, but easily modified.

It might help if you could get the tailpipe emissions measured? And a trace of the lambda signal and the fuel trims.

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Author Topic: Z22XE hesitates at full throttle (Read 4866 times)