hesitation at high speed

Esel · Post by **Esel** » 11 Feb 2016, 23:36

I drive a 97 850GLT long distances. Over the past few months, doing around 70 mph, the car feels like it jumped out of gear for a split second before it starts pulling again. The RPM gauge doesn't move. In a hard climb it does it more often. And the check engine lights flash.
Bad vacuum? I haven't replaced any hoses.

Post by **JDS60R** » 12 Feb 2016, 00:18

Sounds like an ignition misfire. Uphill means a load on the engine. Coil may be arcing to body , ignition wires may be arcingout or spark plugs are too old and need replacement.

Post by **erikv11** » 12 Feb 2016, 00:19

How are the ignition parts (plugs, wires, cap rotor)?

Small vac line holes are usually more of a problem at idle, but for sure it could be something like a leak in an intercooler hose. I would check all of the hoses, those rubber parts are coming up on 20 years old. Especially the funny shaped intercooler hose near the throttle body, that one has been known to tear or when it is old and soft, collapse under boost.

Post by **benpineapple** » 12 Feb 2016, 06:44

I agree, sounds more like a spark issue. How often has this happened? Has the CEL every stayed lit, rather than flash? What codes is it spitting out?

Post by **abscate** » 12 Feb 2016, 07:30

Another vote for ignition

Coil , plug wires, cap rotor spark plugs, and check compression while you are in there

Post by **rspi** » 12 Feb 2016, 07:42

Is this another candidate for the pinned thread?

Post by **erikv11** » 12 Feb 2016, 08:40

Oh, that could be Robert, let's hope not ...

Post by **abscate** » 12 Feb 2016, 11:34

Not with an intermittant miss - I think this has to be something in ignition

Post by **sleddriver** » 12 Feb 2016, 20:33

With the hood open and the engine warmed up, start her up in a dark garage. Using a spray bottle, mist water over the ignition wires & the coil. Look for signs of blue flashes and arcing. It'll be dim, even with your eyes adjusted to the dark, so look carefully. If so, then it's time for new wires (OEM only) and maybe an ignition coil. Hopefully the wires aren't original......

Post by **misha** » 13 Feb 2016, 08:16

sleddriver wrote:...Hopefully the wires aren't original......

Why?
Mine are original and never had a hiccup with 300k+ km.
When ignition system is well maintained,when spark plugs,cap & rotor are in good shape and oem...oem wires almost never go bad.