bad idle and jerky at low speeds when warm

For all technical questions. VIEWABLE without login, you need to register (free) to be able to post a question.
Post Reply
suntzu30
Registered User
Posts: 7
Joined: Fri Dec 21, 2018 9:31 am

bad idle and jerky at low speeds when warm

Post by suntzu30 » Sat Jan 05, 2019 11:30 pm

Hi Guys,

I've managed to buy a 1 owner 94 2.0 Probe with only 69k miles on it, the body work is in a bit of a state but I managed to get it for a low price and fancied a project to do up, on the day I picked it up I ran it up the M6/M74 for about 250 miles and on the motorway is drives lovely.
My issues are though.....

When cold the idle seems fine (about 1800rpm, but on cold I think this is normal) and throttle response is fine, I can drive and release the throttle and get no jerking at all.

When the car is up to temp and I put it into neutral or just dip the clutch the revs will jump from around 800 to 2000rpm a few times then settle at 2000rpm.
Also when warm if I release the throttle to let the car slow down the car jerks, it's more noticeable in lower gears at low speeds.

So far to try and solve the issue I've cleaned the MAF and the throttle body with no change (both seems pretty clean to start with though)
I've ordered a new MAF that should hopefully come within a couple of weeks, when looking at the sensor it seemed like it was slightly offset by around 20 degrees, the images of new ones seem like they're more inline so maybe a damaged sensor somehow?
If anyone has a photo of theirs it would be great to compare.

Reading online it might also be the TPS , I might try replacing that next if nobody can advise otherwise however in the UK a sensor is around £100 for the 16v model, in the US I can get a new one around $40 for the 2.0 - is the same sensor used on both US and UK models?

any other feedback would be great too

Sunfly
Full Member
Posts: 993
Joined: Fri Sep 07, 2018 9:11 am
Been thanked: 21 times

Re: bad idle and jerky at low speeds when warm

Post by Sunfly » Sun Jan 06, 2019 12:35 am

Might be a few things going on there.

First check the coolant level is correct and there is flow through the IAC valve on the throttle body.
The IAC valve itself, might be sticking as the 16v was prone to that problem in my experience.
The idle speed obviously needs checking and setting up to the book.
I'm always suspicious about the distributor module when rough running is a factor but look at the other three first.

Good luck

mikenali
Registered User
Posts: 76
Joined: Mon Oct 22, 2018 12:31 pm
Been thanked: 1 time

Re: bad idle and jerky at low speeds when warm

Post by mikenali » Sun Jan 06, 2019 10:59 am

As Sunfly says, first thing to check with idling issues is coolant levels.

I'd then do the basics. Spark plug gaps, check ignition timing. Set the TPS.

As for spares, this place is the best for spares. There's always a few breaking Probes on here.

suntzu30
Registered User
Posts: 7
Joined: Fri Dec 21, 2018 9:31 am

Re: bad idle and jerky at low speeds when warm

Post by suntzu30 » Sun Jan 06, 2019 1:39 pm

perfect thanks for the feedback guys, I'll check those out as soon as I can.
Tested the cold revs this morning to double check and it sits around 1400rpm when cold not 1800 as I said before, took it for a run around the block and it's still running fine when cold so will checkout the coolant levels first as it's the quickest thing to do.

suntzu30
Registered User
Posts: 7
Joined: Fri Dec 21, 2018 9:31 am

Re: bad idle and jerky at low speeds when warm

Post by suntzu30 » Sat Jan 12, 2019 1:33 pm

thanks again for the feedback guys, checked the coolant right away and it was sitting sitting at the max level as it has been since I got the car a few weeks ago, check the idle valve and gave it a little clean but to be honest it wasn't that dirty at all and appears to move freely. checking the timing isn't something I'm sure how to do so I might leave that until last and get a garage to check it.
MAF and air intake sensors are on the way so I'm waiting on those.

However it's time for a stupid question, while checking everything out I noticed a wire harness sitting not connected to anything, I traced that and found the other end and it was the O2 sensor, pretty strange but I thought wow what an easy fix - connected it up and took it for a drive but sadly the car felt no different, came back and disconnected the battery and pressed the break to reset the ECU since it's been driven for atleast a couple of hundred miles like this - the bad idle and jerk when hot are still the same though. My question is do you think that this sensor could be the issue?
Just thinking I should feel some kind of difference with it connected

jrh
Full Member
Posts: 958
Joined: Thu Sep 20, 2018 3:08 pm
Been thanked: 36 times

Re: bad idle and jerky at low speeds when warm

Post by jrh » Sat Jan 12, 2019 4:47 pm

I've driven my 24V with both O2 sensors U/S for the last 150,000miles.
No problem passing MoT , 38mpg normal driving.
Short period at 1300rpm then smooth idle at 650rev/min.

suntzu30
Registered User
Posts: 7
Joined: Fri Dec 21, 2018 9:31 am

Re: bad idle and jerky at low speeds when warm

Post by suntzu30 » Sat Jan 12, 2019 4:51 pm

Ah ok so most likely not that at fault for me then, will wait on the maf and air intake sensor coming, I did notice a little bit of corrosion on part of the maf solder inside it so I'm crossing my fingers it's as simple as swapping thst out.
Thanks for the feedback

Post Reply

Who is online

Users browsing this forum: No registered users and 31 guests