Ok, so a week ago my disco 2 didn’t wanted to start, it cranks but no start. I changed coils, wires, plugs, fuel pump and nothing. Then I started to play with the starter cables and change the battery and the car started. It was after a few cranks and it was rough at idle. Then I clean the throttle body, IAC valve and change air filter and the car ran perfect for a little more than a week. Today on my way back from work the disco start misfiring at idle, pretty bad. Got home turn it off and now it doesn’t want to start again. No check engine light or anything, I plugged the scanner in and it gave me 4 pending codes. P0300, p0304, p0305, p0302. Same codes that it had when the problem started a couple weeks ago. Also I can hear the IAC valve humming pretty loud when The key is in on position. Any thoughts?

 

bad CPS?

 

Hi Xrad, 2 new ones already. Not even a month old.

 

Bosch or no name? I will NEVER trust a no name CPS on a D2/P38!

 

Bosh. Both. One was new and I went I replaced it just to confirm it wasn’t defective. Same problem. I think my starter is going bad because before that it was starting very slow, sounding like a death battery. But after 2 cranks it started right up. But what about the stalling and misfires codes? And is cranking good, it just not fires up.

 

From the RAVE manual...
P0300 Random/multiple cylinder excess emissions detected / Excess emissions detected on more than one cylinder
P0302 Cylinder 2 misfire detected / Excess emissions level of misfire detected on cylinder No.2
P0303 Cylinder 3 misfire detected / Excess emissions level of misfire detected on cylinder No.3
P0304 Cylinder 4 misfire detected / Excess emissions level of misfire detected on cylinder No.4

What is your current battery voltage? If it is less than 12.6VDC, fully charge your battery. Check your all your battery connections are tight and with no corrosion. Check the cables going to the starter, alternator, rear engine coil packs and spark plug leads.

 

Ok! So that is probably not the issue. side note: I just replaced an original broken bosch with a walker. Works perfectly.

Bad engine ground?

Someone had similar issue a few months ago, but it was cam sensor......

 

You might wanna carry a spare XRad lol just saying. I normally get the CPS from Auto Zone and I verify it's a Bosch unit in the box. Well one time I was in a hurry and didn't check. Got home and it was a no name like BWD or something. I figured it was time to experiment! I slapped it in, and for 2-3 months all was well. Then I took my wife on a weekend Anniversary trip and wouldn't you know it the CPS decides to act up.... I was able to let it cool and get it started again finally. I got home, pulled it, and took it back to Auto Zone for a free replacement. This time I checked the CPS and it was a Bosch unit. It's been nearly 4 years now without a single issue.

 

Battery is a brand new( not even a week old) optima. Pretty sure battery is good. Is cranking strong. I’ll check all cables again but the first time this happened I checked all the grounds and all of them were fine, tight and corrosion free. The ones at the starter are the only ones I haven’t clean yet. But why the misfires codes?

 

Misfire codes are possibly the result of poor ignition. It sounds like a flakey connection somewhere. Based on everything else you've already checked or changed, I'd check the ECU connectors and look for wiring faults in the harness. Don't think I saw a mention of the CKPS though, how's that? Have you verified fuel pressure or just replaced the pump?