Erratic Revving - 1.9 8V Jetronic

[happygoron 2]

Afternoon all,

 

 

 

Car started developing what I thought was a misfire a few weeks back, when accelerating under load she would sometimes cough and jerk. Had a look and did some reading and many said that the commron problem was dieing ignition amp or coil, so I sourced one of each and bought some new plugs as well.

 

 

Changed the coil yesterday, took her for a spin, no change, still jerked badly when taking a low speed uphill corner in 2nd. Next step change plugs, old ones were black and not that old so turned down the fuelling as well. Problem was still there, and worse, she's started revving erratically when not even under load now. Changed amp today with thermal paste and no different. Started checking things methodically (cap, leads) then got to AFM and decided to turn fuelling back up a little and she stalled. So I'm thinking the AFM is on her way out. Any other opinions? video of problem is below, I'm slowly increasing throttle tll 3k ish when she goes tits.

 

 

 

Any south wales members have a spare 1.9 afm I could try?

 

 

Cheers in advance

Neil

[starky5 18]

I had a similar problem a few weeks back when around 3000rpm it would cough like a misfire. I found my oil filler/breather pipes were perished and kinked so changed them and it solved the problem, im guessing the engine couldn't breath properly causing the cough.

[welshpug 1,657]

i'd go with AFM, might have a. 1.9 one here somewhere.

 

definitely something not right with the ignition though, maybe a loose connection for wire 112 as the tacho does strange stuff towards the end of the vid.

[happygoron 2]

Cheers Starkey, I'll have a clean.

 

i'd go with AFM, might have a. 1.9 one here somewhere.

 

definitely something not right with the ignition though, maybe a loose connection for wire 112 as the tacho does strange stuff towards the end of the vid.

 

The tacho makes me think it's ignition related, but I certinally don't think the AFM is helping.

 

 

It's hard to tell if the revs are rising in relation to the tacho, in the video it sounds like they arn't but in the car is sometimes feels like they are, though I'm far from sure as it kicks so much when the revs drop back. However if it's ignition I've changes plugs, amp and coil to no avail and leads look fine, though I have some old but ok ones I could try swapping over. Nothing else to really change bar dizzy is there so assuming it is ignition it'll probably be a loose connection?

 

 

112 is coil/tachy relay to instruments yea? I'll have to have a bit of a search as I don't have a tachemetric relay in the same way as the wirining diagram I don't think. Will look.

 

Will acquire an AFM asap to confirm/deny.

[welshpug 1,657]

112 indeed

[happygoron 2]

112 indeed

 

 

For closure it appears it was the AFM. Many thanks to hexhamstu.