1998 V70 Hesitation after Tuneup - Coil?

echase76 · Post by **echase76** » 30 Oct 2016, 20:13

I tuned up my 1998 V70 today and now I have a hesitation. There was nothing wrong with it previously, just felt like it was dragging a bit and the ignition parts were due to be replaced. After replacing wires, plugs, cap and rotor I now have an intermittent hesitation under load, especially noticeable at WOT. Nothing when letting off. Idle is perfect, except for the very minor, very occasional hiccup.

All parts were replaced with identical branded parts. Cap and Rotor - Bosch, Wires - Bougicord, Plugs - Volvo OEM

I'm now wondering about the coil?? In the dark tonight I can see faint flashing on both sides of the coil and the housing has some white buildup in the same areas. Could this be the culprit?

Eric

160,000 on original coil

Post by **E Showell** » 30 Oct 2016, 20:33

I guess it could be, but I was told a while back that a coil is either good or bad, no in between. Don't know whether that is the case, however.

echase76 · Post by **echase76** » 30 Oct 2016, 20:45

I saw a similar statement on the IPD site, but saw contradictory info here indicating they can get weak. Tomorrow I plan to check coil resistance and also check my work from today. I just realized that I didn't check the sparkplug gaps. They should have been pre-gaped, but I didn't verify.

Post by **cn90** » 30 Oct 2016, 21:01

The single ignition coil in the 1993-1998 850-S70-V70 series virtually never goes wrong.
So...
1. I'd put the original coil back and see what happens.
2. Double-check the distributor cap wire numbering #1-#5.
It is easy to mix it up.
Photo in forum.

echase76 · Post by **echase76** » 30 Oct 2016, 21:43

Cn90 - The coil is original. Didn't replace that. Trying to understand if under load an old coil could cause issues with everything else being new.

I numbered all my wires and double checked my work. However my two year old was "helping" so I will double check in morning. I assume it would run rough all the time if I crossed wires.

Post by **cn90** » 31 Oct 2016, 04:23

"Hesitation on WOT", I'd check:

- Throttle body (clean it)
- Fuel Filter: how old is it?
- Fuel Pump: hoe old is it?
- Air filter?

Post by **erikv11** » 31 Oct 2016, 08:36

It's not crossed ignition wires, OP you are correct that doesn't match the symptoms at all. Checking the coil is a good idea, it is true they rarely go bad so I would try swapping in another used one, is the junkyard easy to get to for you? You're also right that the plugs are almost certainly properly gapped but now you will want to check that.

I would definitely look for dislodged vacuum hoses, or a slightly loose clamp on an intercooler hose. Check all the parts in the area(s) you were working in, if you haven't already.

Post by **misha** » 31 Oct 2016, 11:52

I see from your signature that v70 is T5.
Did you bought oem Volvo spark plugs for Turbo engine?
Single prong?
Coil flashing in the dark is certailnly showing that it's bad...but why now with new parts?

Post by **sleddriver** » 31 Oct 2016, 13:05

echase76 wrote:I tuned up my 1998 V70 today and now I have a hesitation. There was nothing wrong with it previously...... After replacing wires, plugs, cap and rotor I now have an intermittent hesitation under load, especially noticeable at WOT.

My money is on your coil wire being too close OR parallel to the wiring for either the crank position sensor OR the camshaft position sensor. You want to route the coil wire so it's as far away as possible from either one.

echase76 · Post by **echase76** » 31 Oct 2016, 13:09

Quick update. Checked gaps on the OEM plugs and they were all good. All the parts were for a T5 from the FCP tuneup kit. Volvo OEM R6 plugs. As I said it was running ok before with no hesitation, but it had been 50k since anything had been done with cap, rotors, etc.

Checked coil and secondary was 7,500 ohms which is a little low. Primary was ok. While I was in there I took everything apart and put it back together. This time it ran better, but did throw a misfire on cylinder 1 at WOT.

Got home and found the FPR elbow at the manifold crumbling. Maybe that is the issue? will replace and update before buying a new coil.

Will also check wire routing sleddriver