It's electrifying-any similarity to John Travolta is purely coincidental!

The thing that sparked (ugh) this article is a customers car that just won't run right. After changing many components and parts the car is still misfiring. I suggested lifting the bonnet at night to see if there were any stray blue sparks. Well a firework show was what was seen, we are still investigating. Getting a spark problem? Or the occasional hiccup? (stop drinking) Or do you feel the need to mess with your car again? READ ON......................

Focus on the plugs, leads, cap and rotor, maybe even the coil. First off, you must remember that these C4 engines (and any other come to that ) work best if the 'fire' is good. Plugs. Make sure you have the correct spark plugs, if you are not sure how old they are then replace them. I always use Delco ones, but many other equivalent plugs are available. C4 owners may not realise that #6 & #8 plugs are nightmares to get to, small ratchets and short extensions work best here, I also have had limited success with one of those side winder things. I have, before now, got to #6 & #8 from underneath, jacking the car up and laying down and grunting a lot (!). Watch out for all the sensor wires and other clips and pipes etc, it can be a VERY frustrating and painful exercise. I have taken 2 hours a bank on LT1's before now, so be aware of what you are letting yourself in for. Leads. The stock GM leads whilst they are good , do suffer with internal breakdown and need to be replaced if there is any doubt about them. You could check resistance with an ohm meter to see if they have failed or are failing, good leads should show no resistance. Make a very careful note of the placement of the wires especially around the distributor. Also ensure they go on the cap in the correct place. Wrongly placed or positioned leads can produce much frustration tracing a bad running problem. When changing LT1's leads, be aware that the connections to the Optispark unit on the front of the engine are very difficult & time consuming to get to. Lubrication is important (!!!!) so get that silicone grease slapped on to stop your boots sticking (!!) OK who can recite Chevy V8 firing order (if you can you may be a sad person - I have to look it up) For the record my note permanently on the lid of my toolbox says 1-8 4-3-6-5-7-2.

Distributor Cap & Rotor. C4 cars suffer with loose terminals in the cap (oooh miss's!), whilst this is not major problem, it leads (no pun intended) to inaccurate spark transfer, the cap is a cheap item and well worth replacing. Note that the coil is mounted within the cap (double contraception!) and needs to be changed over.

The coil rarely gives problems, but can occasionally fail when hot, hi-power coils are available, but I reckon GM ones work well. enough. The rotor can show signs of wear on the tip (don't we all!) and again its cheap so just replace it, you could just clean it up though. Running problems or trouble codes Code 42 can be due to the HEI module failing in the distributor, it just gets hot and fails, simple replacement is the only way around this.Other codes require a bit more investigation.

Preventative maintenance. Any of you who have found it difficult or impossible to remove those three little torx bolts holding the plenum extension on above the distributor, will want to know what to do. Well, a sharp tap on the head (good for water on the brain!) may shock the bolt to come out, drilling may be the final answer. However, once out, these bolts need some copper ease or similar on them to prevent the bolts remaining in place forever in the future. The plug wire clips are VERY fragile, especially when they are old, they get brittle, so remove them carefully, noting where they go when replacing them. Some, especially behind the distributor are real pains and seem to serve no purpose, so I never normally put them back. Replacements are available but I have found the 2 gang clips hard to get. Hopefully after new plugs, leads, cap, rotor (possibly a coil) the car will run a lot better.

A case in point was my Callaway, I had a misfire at certain revs, changed the original leads (12 years old) and bingo, a new car with even more wow performance than before, Trax at Silverstone proved the point , my 2nd run was 5.1 seconds 0-60, not bad for a 12 year old unmodified car. New Callaway factory time (presumably with little regard to clutch and trans life) was quoted at 4.6 secs.

Of course, following this hard work, you must then test drive the car - this is paramount to any work carried out using these tech tips pages - as always select a venue (read Pub) to drive to, even take your partner to make up for the care and attention you are giving to your (Euro) 'Vette.

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