Engine: 2.5: - baffled by surge - Page 2

tony209 · May 22nd, 2018, 13:36

I've recently been experiencing a similar problem with my C70 T5 AW55 box. Occasionally, it seems to have 'pensioner' moment and takes a second (or probably less) to select a gear when changing up to 2nd or probably 3rd during gentle acceleration. Rev counter hits around 2,500 revs and the gear engages and yet no issues when I drive hard. I was wondering if it is a throttle position sensor problem?

Baffler · May 23rd, 2018, 00:29

Quote:

Originally Posted by jack taylor

Hi Liam, Good to hear from you and thanks for directing me to Cpt Jacks post. What concerns me is the fact that my g/box has been faultless for the last 7 years and has only just decided to bugger about in the last week. There must be a fault; its trying to ascertain what it is.
I dont think its mechanical which only leaves electrical and in that regard, I havent a clue. Perhaps someone on here can throw out a few suggestions.jack

I'm correct in saying you just had the PCV replaced...take it back to the mechanic and ask him to check it over as a plug/pipe/hose may have popped off since the PCV replacement. It's not uncommon for this to happen after such a strip down and, I'm sure, if you had paid main dealer labour charges you'd be standing in the service dept. as we speak

jack taylor · May 24th, 2018, 02:24

Hi Liam, Thanks for that I shall see my mechanic tomorrow. When my donor engine/ gearbox was fitted the mechanics may have only topped up the fluid rather than flushing it. I think I will get this flushed through. From reading so many threads it seems that many problems can be cured by a flush and new oil.
Am I right that fully synthetic oil is required up to JWS 3309 spec.thanks jack.

jack taylor · Jul 26th, 2018, 21:13

At the same time the engine surge started the brake light switch failed. This was replaced about a week later and the engine surge stopped completely.
I thought it was a coincidence but 1,400 miles later the engine surge has not returned. Is it possible that the two are in some way linked or am I having another senior moment.

ITSv40 · Jul 27th, 2018, 16:55

Quote:

Originally Posted by jack taylor

At the same time the engine surge started the brake light switch failed. This was replaced about a week later and the engine surge stopped completely.
I thought it was a coincidence but 1,400 miles later the engine surge has not returned. Is it possible that the two are in some way linked or am I having another senior moment.

If it was the brake position switch on the servo, yes the two could be related.

jack taylor · Jul 28th, 2018, 21:22

Hi ITSv40, the switch is that which is under the brake pedal. could the two be linked.

ITSv40 · Jul 29th, 2018, 13:40

Quote:

Originally Posted by jack taylor

Hi ITSv40, the switch is that which is under the brake pedal. could the two be linked.

In that case the answer is no. That switch is just a stand alone mechanical switch to operate the brake lights when the pedal is depressed. I was thinking if it was the position switch on the servo it could possibly affect the servo vacuum and hence the general operation of the vacuum lines resulting in the surging.

May 22nd, 2018, 13:36	#11
tony209 Master Member Last Online: Aug 3rd, 2023 09:39 Join Date: Jun 2014 Location: Chesterfield	I've recently been experiencing a similar problem with my C70 T5 AW55 box. Occasionally, it seems to have 'pensioner' moment and takes a second (or probably less) to select a gear when changing up to 2nd or probably 3rd during gentle acceleration. Rev counter hits around 2,500 revs and the gear engages and yet no issues when I drive hard. I was wondering if it is a throttle position sensor problem? __________________ 02 V70 2.4 Torslander Nautic blue, black leather, rear spoiler and tethys 17" wheels 03 C70 2.4 T GT Convertible Nautic blue, blue roof, beige leather. SOLD 05 C70 2.3 T5 GT Convertible Silver, black roof, black (grey leather) Collection interior

May 24th, 2018, 02:24	#13
jack taylor Master Member Last Online: May 15th, 2022 15:53 Join Date: Jan 2008 Location: Torrenueva, Costa del Sol	Hi Liam, Thanks for that I shall see my mechanic tomorrow. When my donor engine/ gearbox was fitted the mechanics may have only topped up the fluid rather than flushing it. I think I will get this flushed through. From reading so many threads it seems that many problems can be cured by a flush and new oil. Am I right that fully synthetic oil is required up to JWS 3309 spec.thanks jack.

Jul 26th, 2018, 21:13	#14
jack taylor Master Member Last Online: May 15th, 2022 15:53 Join Date: Jan 2008 Location: Torrenueva, Costa del Sol	At the same time the engine surge started the brake light switch failed. This was replaced about a week later and the engine surge stopped completely. I thought it was a coincidence but 1,400 miles later the engine surge has not returned. Is it possible that the two are in some way linked or am I having another senior moment.

Jul 28th, 2018, 21:22	#16
jack taylor Master Member Last Online: May 15th, 2022 15:53 Join Date: Jan 2008 Location: Torrenueva, Costa del Sol	Hi ITSv40, the switch is that which is under the brake pedal. could the two be linked.

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