misfiring 400se

[Jim Meehan]

Cant you just tell i am new to all this! Shadowfax is lame. Before I bought, as seller drove car, misfire occurred. Peter, lovely guy, was embarrassed. I thought nice car but not with a dodgy engine management system. Went away. Rang later to find he had got new plugs, leads, dizzy and rotor and coil. Sorted. Bought car. 36000 miles since new. I have done 4oo miles in 2 weeks since bought and this eve for first time since, misfiring again. Has had mix of basic unleaded and optimax ( shell + bp ) but that was for previous 70 mile or so before recent misbehaviour. Any ideas?

[jmorgan]

Every thing good and tight electrical wise? I had a loose lead from the coil to the dizy cap. That is the lead into the dizzy was slack. Expanded the metal end with a screwdriver and worked fine.

[Boosted LS1]

I'd usually suspect an electrical fault, plugs leads etc. What does the engine bay look like in the dark? Can you see any sparks arcing across the leads to the engine rocker covers? If not, I'd look at the low tension side for duff connections etc.

[Seamus]

Had a similar problem with one of the daily hacks recently - having replaced the dizzy cap it seems it had cracked within only a few weeks of fitting! could clearly see the spark out of the side of where the HT lead connects.. hopefully it will be something as straight forward for you.

[danny hoffman]

Check the multiplug that goes into the ecu (above the passenger footwell)

[NHyde]

Jim ,

Is the 400 a " hotwire" engine ?

....................... altogether now !!!!

[jim meehan]

Was sound at tickover, no arcs in the dark in garage. Took out this morning, sound as a pound. Found condenser affixed to coil/body bolt needs tightening. Will do check of joins above passenger footwell in the light Grateful as ever folks

[jim meehan]

NHyde said:

Jim , Is the 400 a " hotwire" engine ? ....................... altogether now !!!!

Er......what's that again?

[nick heppinstall]

Hi Jim. As all above. Also spend a few hours going around every electrical connection and earth you can find and cleaning 'em up until they are nice and shiny. Book yourself in for a massage beforehand though 'cause your back will ache like #uck after !

Edited because Id not read your posts properly ! I'd still clean everything up though....

>> Edited by nick heppinstall on Thursday 18th March 21:33

[wedg1e]

Worst case scenario, if the misfire comes and goes, is a dry joint on the ECU. Any half-competent electronics bod should be able to strip the ECU and resolder the entire boards in half an hour.

Ian

[SLB]

Had a similar thing on my SEAC a few years back. Gradually got worse until it cut out altogether going round a bumpy bend. It was about a year after the engine had been out for a new clutch and I traced it to two loose earthing? leads on the near side rear of the engine. I believe the service chap had only done them finger tight when he put the engine back.

[jmorgan]

jim meehan said:

NHyde said: Jim , Is the 400 a " hotwire" engine ? ....................... altogether now !!!! Er......what's that again?

They all do that sir?