: Rough idle on cold start-up



97d'elegance
12-29-04, 07:23 PM
When I start my car after it's been sitting over night ... or at the office all day it runs rough for about 10 seconds ... it just started doing this a day or so ago ... what does this sound like? Fuel Pressure Regulator? No codes

97 Deville D'Elegance

Ranger
12-29-04, 09:59 PM
No. I'd look at plugs and wires first.

BeelzeBob
12-29-04, 10:40 PM
When I start my car after it's been sitting over night ... or at the office all day it runs rough for about 10 seconds ... it just started doing this a day or so ago ... what does this sound like? Fuel Pressure Regulator? No codes

97 Deville D'Elegance


Could be. So easy to check you might as well. Disconnect the vacuum line to the fuel pressure regulator while the engine is idling. Watch the vacuum nipple on the FPR for any sign of fuel seepage for several minutes. Shut down the engine with the line still off and watch the vac nipple on the FPR for several more minutes.

97d'elegance
01-01-05, 08:15 PM
The Fuel Pressure Regulator checks out okay ... It also now runs rough after almost every start ... even a warm start but smooths out on it's own or if I mash the gas a bit ... any other suggestions?

Thanks

Ranger
01-01-05, 08:32 PM
Did you just have your fuel rail replaced?

97d'elegance
01-02-05, 09:50 AM
Yes, the fuel rail was replaced about a month and a half ago.

Spyder
01-02-05, 11:48 AM
I'm betting that its most likely plug wires...they get bounced around and moved during the fuel rail replacement and the older wires don't work right anymore. Lots on here have had the same problem. Use AC Delco wires!!! not the el cheapo ones.

mcowden
01-02-05, 01:23 PM
To back up Ranger's statement, I was having about the same problem you describe. It ran rough for between 20 and 60 seconds after startup if it hadn't been run for a couple days. I just ignored it until it started happening every day. Then I replaced the wires with new AC Delcos (part #748J) and the plugs with new AC Delcos (part #41950) and the thing runs perfectly at all times. The difference is amazing. I wouldn't have complained about the way it ran before, but it's definitely much better now. Starts faster, never stumbles at startup anymore, everything is great. I agree 100%. Go for the plugs and wires first if the FPR checks out good, and use the parts that were designed for the engine. Avoid the Bosch plugs and aftermarket wires. AC Delcos all the way. If you do it yourself, just be careful not to overtorque the plugs and route the wires carefully, especially on the rear bank, to avoid letting them hit the exhaust manifold. That will probably fix it right up for under $200 if you do it yourself. You can order the plugs and wires from www.rockauto.com for $5.66/each and $116.79, respectively.

M C
:cheers:

97d'elegance
01-02-05, 03:43 PM
I will order OEM parts and put them on this next weekend. Hoping it's as easy as everyone says .. the Cadillac dealership quoted (4) hours to replace the plugs and wires ... does it really take this long? Thanks for the help.

Ranger
01-02-05, 07:17 PM
4 HOURS! YIKES! Shouldn't take you much more than an hour, two at the outside if you are really slow and carefull. A Caddy mechanic could probably do it in :30 min.

Spyder is right. I had a misfire develope right after the fuel rail replacement. New wires took care of it. I am pretty sure the misfire also took out the blower motor not long after. They are very susepable to EMI. If you have the original blower motor, do not let the wires lay any closer than neccassary to it. The new ones are redisigned and won't be affected but they are expensive and a PITA to install.

97d'elegance
01-02-05, 07:30 PM
Kinda sucks that everyone is having to pay for wires after a recall is completed. Would be nice it they would have replaced them as well since they damaged them during the removal. I have no idea if the blower motor is original but thanks for the "heads up" ... I'll be extra careful .. one more thing ... when they replaced the fuel rail they put protectors on all the plug wires leading toward the front of the car. I'm assuming I should put these on the new ones as well?