Hiccup under hard acceleration

shaneimus · 29th March 2016, 18:50

Hi all. Experienced something odd on the way home today. I was accelerating in second gear and as the revs were building, just before I shifted up, there was a strange hiccup and a jolt. Changed to third and the car ran fine all the way home. Any ideas?

stevestrat · 29th March 2016, 18:59

I see you have a 1.8T, hesitation under hard acceleration usually indicates a dodgy coil pack.

Avulon · 29th March 2016, 19:22

Excessive spark plug gap. Failing coil pack or leadOr the start of HGF.

Some have found that the recommended 1mm plug gap gave the hesitation but closing it to .5 to .75 cured it (probably an early sign of coil deterioration)

shaneimus · 29th March 2016, 19:27

I hope it's not HGF, the service history indicates it was only done two years ago. How easy would it be to tackle the coil pack?

Avulon · 29th March 2016, 22:46

Quote:

Originally Posted by shaneimus

I hope it's not HGF, the service history indicates it was only done two years ago. How easy would it be to tackle the coil pack?

Extremely easy, but check the plugs first (you have to remove the coil packs to do that). Two screws to remove the cover then you'll see the two coil packs each held with two bolts - take note of where the leads go and how they run before removing them - go carefull releasing the low tension wiring from the clips (you'll see as you are doing it) pull the leads and coil packs away and move them out of the way (leave 'arranged' to make easier to put back) then remove and check the plugs.

Ste.Sales · 30th March 2016, 08:48

Where in the rev range did it hiccup? 3500rpm ish? Could well be boost controller.... Or more likely the vacuum lines from it to the turbo? If these are ok, then i agree with the above, coil packs.
Steve

Synchromesh · 30th March 2016, 17:57

Mine did that and it was caused by the waste gate link being seized causing it to over boost so it temporarily cut the ignition.

Have a look at the posts titled 1.8T Actuator servicing.

Sheraton · 31st March 2016, 15:03

I had this when i bought my car (75 1.8t) - i had a stuttering(misfire) that i could power through - caused by a spark issue (oil in the plug well) cleared the oil, fixed the leak (loose rocker cover bolt) and gapped plugs to 0.80mm while i was there - this cured that issue

I also had a different loss of power under full throttle - less of an engine misfire, more of an engine cut-out symptom. this became more evident and at worse was violent loss of power at full throttle.

i figured out it was turbo overboost, causing the ecu to cut power.
changed the boost control vac hoses - no fix
tested the wastegate actuator using a bicycle pump - remove the vac hose from the boost control solenoid (the one connected to the wastegate actuator) attach the pump and pressurise - you should see the actuator moving between the exhaust manifold.
my actuator was fine - so i bypassed the boost control solenoid and connected the turbo compressor to the wastegate actuator (using the short vac hose from the boost control solenoid) this eliminated the problem of engine cut-out and diagnosed(correctly) the problem was overboost cut-out due to a failing boost control solenoid - ordered a new one for £24 delivered and cured the problem

Paul..

29th March 2016, 18:50	#1
shaneimus Regular poster MGZT Join Date: Aug 2015 Location: Swadlincote Posts: 82 Thanks: 7 Thanked 6 Times in 6 Posts	Hiccup under hard acceleration Hi all. Experienced something odd on the way home today. I was accelerating in second gear and as the revs were building, just before I shifted up, there was a strange hiccup and a jolt. Changed to third and the car ran fine all the way home. Any ideas?

29th March 2016, 18:59	#2
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,484 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	I see you have a 1.8T, hesitation under hard acceleration usually indicates a dodgy coil pack. __________________ Steve T4 Location Map

29th March 2016, 19:22	#3
Avulon This is my second home 1.8t Tourer Join Date: Oct 2011 Location: Tanelorn Posts: 4,830 Thanks: 956 Thanked 1,148 Times in 916 Posts	Excessive spark plug gap. Failing coil pack or leadOr the start of HGF. Some have found that the recommended 1mm plug gap gave the hesitation but closing it to .5 to .75 cured it (probably an early sign of coil deterioration) __________________ Need a T4 ?: T4 Owners Map thanks to Stevestrat ( use at your own risk) Where?: https://en.wikipedia.org/wiki/Tanelorn Mods/Retrofits: PCV vortex 'filter'; bluetooth; inline thermostat; reversing sensors; plenum spyhole ; headlamp washers ; Diy mp3 player replacing CD multichanger; FBH with remote; Headlamp washers; black/chrome front grille, rear blind; Xenon projectors To do: puddle lights; 2 Din cd/nav to fit; boot release button

30th March 2016, 17:57	#7
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 624 Thanks: 50 Thanked 44 Times in 32 Posts	Mine did that and it was caused by the waste gate link being seized causing it to over boost so it temporarily cut the ignition. Have a look at the posts titled 1.8T Actuator servicing. Last edited by Synchromesh; 31st March 2016 at 11:44.. Reason: Previous post reference added.

29th March 2016, 19:27	#4
shaneimus Regular poster MGZT Join Date: Aug 2015 Location: Swadlincote Posts: 82 Thanks: 7 Thanked 6 Times in 6 Posts	I hope it's not HGF, the service history indicates it was only done two years ago. How easy would it be to tackle the coil pack?

30th March 2016, 08:48	#6
Ste.Sales Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Preston Posts: 233 Thanks: 9 Thanked 37 Times in 35 Posts	Where in the rev range did it hiccup? 3500rpm ish? Could well be boost controller.... Or more likely the vacuum lines from it to the turbo? If these are ok, then i agree with the above, coil packs. Steve

31st March 2016, 15:03	#8
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 had this when i bought my car (75 1.8t) - i had a stuttering(misfire) that i could power through - caused by a spark issue (oil in the plug well) cleared the oil, fixed the leak (loose rocker cover bolt) and gapped plugs to 0.80mm while i was there - this cured that issue I also had a different loss of power under full throttle - less of an engine misfire, more of an engine cut-out symptom. this became more evident and at worse was violent loss of power at full throttle. i figured out it was turbo overboost, causing the ecu to cut power. changed the boost control vac hoses - no fix tested the wastegate actuator using a bicycle pump - remove the vac hose from the boost control solenoid (the one connected to the wastegate actuator) attach the pump and pressurise - you should see the actuator moving between the exhaust manifold. my actuator was fine - so i bypassed the boost control solenoid and connected the turbo compressor to the wastegate actuator (using the short vac hose from the boost control solenoid) this eliminated the problem of engine cut-out and diagnosed(correctly) the problem was overboost cut-out due to a failing boost control solenoid - ordered a new one for £24 delivered and cured the problem Paul..