1.8 auto hesitant for short while after starting

brianw · 19th August 2018, 14:10

My Wifes car has been having a problem lately.
It starts on the button but idle is typically not as smooth as usual initially.
It is then hesitant on pulling away e.g at junctions.
Sort of nothing there then it will pull as normal.
After a couple of minutes the symtoms dissappear and then it drives normally.
It used to only do this on first start in the morning and would be normal on subsequent startups.
The last week it has sometimes done it when startinf after a few hours rest.

I suspected it could be the inlet manifold gasket and I changed that yesterday but it is no different.

Does anyone know of anything else that could be at play during the initial couple of minutes after starting to cause this?

I checked the coolant temp readout on using the obd and the readings obtained seem inline with the aftermarket digital coolant temperature readout i have fitted (temp sensor on heater inlet pipe)

I was wondering whether to remove the spark plugs first thing in the morning and operate the starter to see if any water was ejected from cylinders.
If i were to try this is it ok to just disconnect the connectors to the coil packs to do it?
I do not want to mess up anything while testing.

I was also wondering if as it is an auto if there were any auto specific sensors that could be causing the symptoms.

Brian

Dawn · 19th August 2018, 16:18

I once had a Cavalier do that and it was the IAC playing up. Don't know what these have and if it could be anything like?

suzublu · 19th August 2018, 16:26

Regap the plugs to .75mm

stevestrat · 19th August 2018, 17:54

If its the original plastic inlet manifold they can distort, you'd need to get it off and check it on a flat surface, something like a sheet of glass. If it is distorted no matter how many times you change the gasket you won't stop water leaking into the manifold.

Gigagator · 19th August 2018, 20:54

Quote:

Originally Posted by suzublu

Regap the plugs to .75mm

Apologies for the slight thread hijack, but why do you recommend this?
I’m looking for things to tinker with as for once I’ve got nothing to do on my 75.

I sometimes find my 1.8 can be a bit slow to start (though has never failed to) and there is no rhyme or reason for it. Air temperature, engine temp, fuel level etc have no bearing on it, so I’ve often wondered if it could be a weak spark.

stevestrat · 19th August 2018, 20:57

Recommended gap for the 1.8 and 1.8T is 1mm but you'll find every owner that's had theirs a while has gone to 0.7 - 0.75, the car generally runs better with the smaller gap. Believe it or not yhe best gap can vary according to the individual car, try reducing it in steps.

Sheraton · 19th August 2018, 21:40

I was under the impression the plug gap issue was only relating to the 1.8 Turbo ?

I may be wrong....

..... it's been known.

on my car with 1.0 Gap - there was a slight misfire ONLY on Full Throttle and at high RPM

Paul.

stevestrat · 19th August 2018, 21:49

Thanks for pointing out my c*ck up Paul! Getting confused as I've had both a 1.8 and 1.8T.

brianw · 20th August 2018, 12:10

Thanks to all for the suggestions.

We recently had a misfire/ lack of power problem when pulling away which after replacing plugs (and setting gap at 0.7mm), replacing coil pack, 02 sensor all to no avail it turned out to be a broken wire to the map sensor (outer casing appeared intact until it parted on removal of sensor.
This problem manifested itself all of the time though, not just after start up as it currently does.

I am tending to suspect inlet manifold gasket despite just replacing it.
It will have to wait until the weekend but I propose removing spark plugs to see if any water is ejected on cranking and take it from there.

Brian

19th August 2018, 14:10	#1
brianw Gets stuck in Rover 75 CDT Connoisseur SE Rover 75 1.8 Auto Connie Join Date: Nov 2011 Location: Aldershot Posts: 927 Thanks: 126 Thanked 119 Times in 79 Posts	1.8 auto hesitant for short while after starting My Wifes car has been having a problem lately. It starts on the button but idle is typically not as smooth as usual initially. It is then hesitant on pulling away e.g at junctions. Sort of nothing there then it will pull as normal. After a couple of minutes the symtoms dissappear and then it drives normally. It used to only do this on first start in the morning and would be normal on subsequent startups. The last week it has sometimes done it when startinf after a few hours rest. I suspected it could be the inlet manifold gasket and I changed that yesterday but it is no different. Does anyone know of anything else that could be at play during the initial couple of minutes after starting to cause this? I checked the coolant temp readout on using the obd and the readings obtained seem inline with the aftermarket digital coolant temperature readout i have fitted (temp sensor on heater inlet pipe) I was wondering whether to remove the spark plugs first thing in the morning and operate the starter to see if any water was ejected from cylinders. If i were to try this is it ok to just disconnect the connectors to the coil packs to do it? I do not want to mess up anything while testing. I was also wondering if as it is an auto if there were any auto specific sensors that could be causing the symptoms. Brian

19th August 2018, 17:54	#4
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,502 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	If its the original plastic inlet manifold they can distort, you'd need to get it off and check it on a flat surface, something like a sheet of glass. If it is distorted no matter how many times you change the gasket you won't stop water leaking into the manifold. __________________ Steve T4 Location Map

19th August 2018, 20:57	#6
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,502 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	Recommended gap for the 1.8 and 1.8T is 1mm but you'll find every owner that's had theirs a while has gone to 0.7 - 0.75, the car generally runs better with the smaller gap. Believe it or not yhe best gap can vary according to the individual car, try reducing it in steps. __________________ Steve T4 Location Map Last edited by stevestrat; 19th August 2018 at 21:12..

19th August 2018, 21:49	#8
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,502 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	Thanks for pointing out my cck up Paul! Getting confused as I've had both a 1.8 and 1.8T. __________________ Steve* T4 Location Map

19th August 2018, 16:18	#2
Dawn I really should get out more....... MG ZT 180+ auto Join Date: May 2016 Location: Ilkeston, Derbys Posts: 2,743 Thanks: 285 Thanked 1,128 Times in 504 Posts	I once had a Cavalier do that and it was the IAC playing up. Don't know what these have and if it could be anything like?

19th August 2018, 16:26	#3
suzublu This is my second home rover 75 1.8 vvc club se wedgwood blue Join Date: Aug 2009 Location: Seaton Carew Posts: 26,936 Thanks: 65 Thanked 7,142 Times in 4,642 Posts	Regap the plugs to .75mm

19th August 2018, 21:40	#7
Sheraton Posted a thing or two Rover 75 1.8t Join Date: Oct 2015 Location: Edinburgh Posts: 1,377 Thanks: 384 Thanked 409 Times in 267 Posts	I was under the impression the plug gap issue was only relating to the 1.8 Turbo ? I may be wrong.... ..... it's been known. on my car with 1.0 Gap - there was a slight misfire ONLY on Full Throttle and at high RPM Paul.

20th August 2018, 12:10	#9
brianw Gets stuck in Rover 75 CDT Connoisseur SE Rover 75 1.8 Auto Connie Join Date: Nov 2011 Location: Aldershot Posts: 927 Thanks: 126 Thanked 119 Times in 79 Posts	Thanks to all for the suggestions. We recently had a misfire/ lack of power problem when pulling away which after replacing plugs (and setting gap at 0.7mm), replacing coil pack, 02 sensor all to no avail it turned out to be a broken wire to the map sensor (outer casing appeared intact until it parted on removal of sensor. This problem manifested itself all of the time though, not just after start up as it currently does. I am tending to suspect inlet manifold gasket despite just replacing it. It will have to wait until the weekend but I propose removing spark plugs to see if any water is ejected on cranking and take it from there. Brian