Van Running wierd (popping) and erratic rev counter

[crazyhorse]

Hey guys,

Long time no post. Hope someone can help

Recently the van has developed this strange problem. Idles at just over 1000rpm, but when I put my foot down it pops and hesitates. I can get going slowly and drive at low RPM but when I put my foot down it starts spluttering and pops at the back. The even stranger thing here is when I am driving the tacho fluctuates around the 5000 and 6000rpm or higher but engine sounds normal. It is intermittent, but when driving to work this morning it was a nightmare...

Any suggestions, where to start, I know it could be a dodgy aftermarket tachometer but that wouldnt explain erratic lumpy running. I have checked HT leads, they are within resistance.. any other ideas, I thought maybe coil. I have never replaced this since having the van over 10 years ago..

Thanks guys

[crazyhorse]

As a footnote… drove home tonight, 25 miles and the van didnt miss a beat… so intermittent to say the least

[Mocki]

The fact the rev counter is erratic at the time the misfires happen says the coil is the first place to start looking, as the rev counter gets its signal from the coil directly

[ajsimmo]

But what's making the coil fire so often? It's suggesting dodgy hall sender or wiring to it. Those errant sparks must be going to the wrong plug at the wrong time, causing the popping & power loss.

Sent from my moto g(30) using Tapatalk

[Rosie n' Jim]

The tacho is getting it's  signal from the wire that runs between the distributor and coil,  so could be either, but it's the distributor that generates the signal,  so likely to be the source. I'm not familiar with your engine so can't be more specific.

[crazyhorse]

thanks all for your suggestions.

Will check wiring to it.

In the meantime might replace coil also. I havent changed it since I have had the van..

[crazyhorse]

update (just in case anyone has interest) Drove 25 miles to work this morn, popping and missing in 4th. Home journey tonight, didnt miss a beat.. What the blithering heck?

[Stesaw]

I'd clean the grounds in the engine bay.
Maybe check the dissy cap and arm for damage, vac leaks, I know you said you checked the leads but when you check em give em a bit of a wiggle.

I only say that as I had a misfire on my van very intermittent.. checked the leads all in spec, went through everything tearing my hair out replaced coil with known good, everything.. went back to testing the leads wiggled one and it stopped giving a reading did it a few more times to make sure I wasn't going mad or moving the probes off the connections. The cable had snapped off the end of the connector but it was still touching unless you wiggled it.. so I guess engine vibration made it loose contact

Replaced the lead and its been fine since.

[crazyhorse]

OK, thanks for that, will give it a go tomorrow...

[Stesaw]

Hopefully its something that simple for you..

[what2do]

Any results to report?

[crazyhorse]

Well, I bought 4 new spark plugs… and since the change a week ago it’s been fine… didn’t want to tempt fate.. didn’t change coil either, so fingers crossed

[crazyhorse]

And it’s back…spoke to soon. It’s been fine for a good 1000 miles

Driving yesterday was a pig… erratic rev counter readings and backfire and popping.. will check ht leads

[Mocki]

I would be looking at that coil …….

[hubcap61]

Had a similar issue with my bus a couple of weeks ago driving home from work. Van stuttered, (aftermarket) rev counter went mad and van died. Unplugged rev counter. Wouldn't start. Fitted spare coil I always carry. Started straight up. Connected rev counter and it would'nt fire. Unplugged rev counter . Fired straight away.
Rev counter in the bin. Been running spot on ever since. Ordered another (spare ) coil.