mik666 Posted March 24, 2015 Share Posted March 24, 2015 hey gang - so this is a continuation of an older thread but decided to start afresh. Anyway 87 4.0 2WD - rebuild motor with about 12k on it. After i had changed the injectors and all new plug wires/plugs (all old ones looked fine - no fouling etc)/shocks she started running rough - felt like it was missing on 1 cylinder and sputtered a bit when gas applied. I changed out all the battery cables and cleaned all the ground connections and replaced all my vacuum lines - thought i had it licked, started up and ran sweet, drove it around the block a few time - yup nice!! Well next day took truck to the gym and ran a few errands, when i jumped in it to go home problem resurfaces - crap - rough running, poor acceletration, rough idle. must be the CPS, so get one from rock auto - their most $ one as i don't want to go cheap. put it in (easy to do!), truck fires up - runs sweet - yeah fixed it nice!! Ok run to the Bev mo to get some IPA's to celebrate - runs sweet, great - until i come out of the place and start her up to drive home. CRAP, running rough again, same symptoms as before. Stopped at some little auto repair place blocks from my house on way home - pissed a bit at it- guy looks at it for a few hrs and says yup - its running rough on a cylinder but he's pretty much useless (wants to do a compression check (the problem is intermittent i tell him, and plugs looked fine ) mentions the water pumps is making a noise and tha catalyic converter probabaly isn't the best, but like i said those aren't causing my problems, he agrees and doesn't charge me but makes me realize this is going to have to be a home remedy as shop will be useless with my old truck). The one thing I have noticed that makes me think something strange is up is it never goes from running well to running like crap while driving it - only after shutting it off and then restarting after a bit to head else where (small sample size though). Also a question - could one of the injectors be bad - i've only had them in for a few weeks? any other suggestions? love my truck but loving it a bit less with the problem, which i suspect is a small deal but is driving me crazy thanks as always! Mike Link to comment Share on other sites More sharing options...
Fernando87mj Posted March 24, 2015 Share Posted March 24, 2015 Do you think it could be a problem with heat soak with the injectors ? Also what spark plugs did you use ? These. Engines run beautifully with the champion cooper plugs with the gap @ 0.35 , these engines might not run as well with the fancy new platinum plugs or whatever they're called Link to comment Share on other sites More sharing options...
mik666 Posted March 24, 2015 Author Share Posted March 24, 2015 hey fernando Champion copper plugs, gapped to 0.35 - had the iridium in previously when problem developed and thought it might be the problem so switched to coppers - same thing..... Do you think it could be a problem with heat soak with the injectors ? Also what spark plugs did you use ? These. Engines run beautifully with the champion cooper plugs with the gap @ 0.35 , these engines might not run as well with the fancy new platinum plugs or whatever they're called Link to comment Share on other sites More sharing options...
Fernando87mj Posted March 24, 2015 Share Posted March 24, 2015 Nice ! And Have you tried wrapping the injector with heat shield or temporarily using the old ones to see if the issue disappears ? It also possibly unplugging each injector one at a time to see if there's any diffrence in performance /idle to help determine if there's any bad injectors ? Link to comment Share on other sites More sharing options...
mik666 Posted March 24, 2015 Author Share Posted March 24, 2015 Cool thx fernando i unfortunately chucked the old injectors out, but will try unplugging them individually and see if there is a noticeable change Nice ! And Have you tried wrapping the injector with heat shield or temporarily using the old ones to see if the issue disappears ? It also possibly unplugging each injector one at a time to see if there's any diffrence in performance /idle to help determine if there's any bad injectors ? Link to comment Share on other sites More sharing options...
mik666 Posted March 24, 2015 Author Share Posted March 24, 2015 Guys - after considering Fernando's advice and unplugging each of my injectors one at a time - all of which made an impact on idle etc - i unplugged my new CPS, and of course the engine died immediately - upon replugging the CPS back in and starting the thing it ran smoothly and didn't miss a beat (was running like $#!& before unplugging the thing) - any thought upon possible bad (new) CPS or wires going to it?? any way to determine what the culprit may be, wiring or CPS? thx! Mike Link to comment Share on other sites More sharing options...
ParadiseMJ Posted March 24, 2015 Share Posted March 24, 2015 Since it runs fine when the connecter is messed with it'd be suspicious of the wiring or the connector itself. Have you looked at your sensor grounds, or tested the sensor grounds.? Is the CPS wiring off the manifold? Find Cruiser's tips and do the sensor ground upgrade (or just do the testing) and then the CPS test. Since you replaced vacuum lines I'd also look at the MAP sensor vac line and electrical connection, too. Here it is. http://comancheclub.com/topic/36382-cruisers-renix-tips/ Link to comment Share on other sites More sharing options...
cruiser54 Posted March 25, 2015 Share Posted March 25, 2015 Paradise is on the right track. Also, test your CPS output. Link to comment Share on other sites More sharing options...
mik666 Posted March 25, 2015 Author Share Posted March 25, 2015 great thx guys - work for the weekend! Link to comment Share on other sites More sharing options...
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