[dna.od]

Hi my name is Dan, from San Bernardino. My 95 Deville, 4.9 all of a sudden began running rough while driving. Can maintain speed at any level okay but has a mild stutter, not only when accelerating. While parked w/o load it seems to idle and accelerate fine. Wondered if someone can identify this as a fuel problem (regulator, filter etc) or an electrical (O2 sensor, main brain etc) problem....or at least point me in the right direction?? Vehicle is all stock, 95,000 mi. I have owned it since it was at 60,000 and it has been flawless. Thanks

 

[Cream_Devil_91]

Howdy Dan and welcome to the forums! :welcome:

All the experts here are prob gonna ask for the codes so pull those first...

Here's the link if you don't know how:
http://www.cadillacforums.com/forum...005-including-1985/138257-how-pull-codes.html

Hopefully once you have those you'll be able to narrow it down and can get some help...

 

[dna.od]

All codes are history, nothing current. History P030, 1027,1039,1052. I accelerated again while car was in park. It starts missing at high RPM.

 

[Ranger]

Probably time for a set of plug, wires, cap and rotor.

 

[dna.od]

You think it is as simple as that? If so, that's great! But I was hoping :hmm: NOT to have to start replacing a string of sub-components that are not specifically causing this problem. In other words... the cheapest route. If I took the ignition (what looks like the distributor) apart what would I look for to determine if it's bad?

I would know what to look for with points, cap and rotor but those days are long gone

 

[Ranger]

Just look for spark erosion on the cap contacts. Just like the old days. Plugs and wires are no different. Hard to say for sure if that is your problem, but at 95K it is getting due anyway.

 

[mysedan]

have the EXACT same problem starting just today in fact! In fact mine JUST did it about 10 mins ago on way to store.....except my car decided to shut down driving along....didnt even know it had stalled out till I noticed very heavy steering. coasted to a stopsign and it would start and then stall and die. got it fired up and ran HEAVY throttle and it did ok but could feel it surging, missing at higher RPM, lil sluggish off the line. Got to a parts store and got some Seafoam (love that stuff) and poured about 1/4 can in gas tank and some throttle body cleaner....sprayed that in and it made it home....pretty sure I need plugs and wires also...wouldnt surprise me. Check out your throttle body also...mine was pretty cruddy under the intake...like nasty cruddy. Just another thing I was PLANNING on for the WEEKEND that came a lil sooner than thought

***edit***
I am at 144,xxx miles BTW

 

[mysedan]

have the EXACT same problem starting just today in fact! In fact mine JUST did it about 10 mins ago on way to store.....except my car decided to shut down driving along....didnt even know it had stalled out till I noticed very heavy steering. coasted to a stopsign and it would start and then stall and die. got it fired up and ran HEAVY throttle and it did ok but could feel it surging, missing at higher RPM, lil sluggish off the line. Got to a parts store and got some Seafoam (love that stuff) and poured about 1/4 can in gas tank and some throttle body cleaner....sprayed that in and it made it home....pretty sure I need plugs and wires also...wouldnt surprise me. Check out your throttle body also...mine was pretty cruddy under the intake...like nasty cruddy. Just another thing I was PLANNING on for the WEEKEND that came a lil sooner than thought

***edit***
I am at 144,xxx miles BTW

***x2 edit***
I think I may heave a weak fuel pump possibly...since I go WOT and it chugs some and seems to lose it.....possible trouble there also for you.

 

[pompste]

Probably time for a set of plug, wires, cap and rotor.

Exactly right-----my '95 Deville 4.9 had an idling stutter for a couple of years until i replaced all the listed above.Always best to replace all at once.

 

[cadillac_al]

Probably time for a set of plug, wires, cap and rotor.

At 95,000 miles that stuff is probably all still original and ready for replacement. When I changed my cap and rotor at 180,000 miles I would swear they were original. The worst I had ever seen in my lifetime. My car is still running the original plug wires but only because it runs fine with no problems. If there was the slightest hiccup i will change them. I only mention this in case you want to cheat and just do the plugs and cap/rotor.

 

[dna.od]

The cap and rotor look pretty bad. The plugs look okay although the gap @ .60 looks huge, but since I don't relish the task of r/r-ing the back four I'm just going to start with the cap and rotor.

mysedan: what does WOT mean? (sorry, I'm not up to speed on all the acronyms)

Will let everybody know what the outcome is in next 1/2 hour:bouncy:

 

[dna.od]

Cap and rotor did nothing. :hmm::hmm::hmm:

More descriptive information on the symptoms: in park, at I'm guessing 2500 RPM (plus/minus) the engine begins to stutter in a pulse or lunging rhythm .5 seconds each. It runs fine up till this point.

Does this sound something like a fuel regulator or pump or something like plugs/wires?

 

[mysedan]

Cap and rotor did nothing. :hmm::hmm::hmm:

More descriptive information on the symptoms: in park, at I'm guessing 2500 RPM (plus/minus) the engine begins to stutter in a pulse or lunging rhythm .5 seconds each. It runs fine up till this point.

Does this sound something like a fuel regulator or pump or something like plugs/wires?

Typical old school thought process will sound like your not getting enough fuel pressure....while in drive and driving is it ok? full WOT and all that? Mine was doing the same and "clipping" I guess you could say...in park and at a standstill in parking space...go to open it fully and there ya go...it would clip off and wanna die...I did do a decent albeit "QUICK" TB cleaning and I can drive the car normally right now....but I am going to finish up my cleaning, clean out the tubes with a hanger and a toothbrush for the blades and all...and see if that helps any first.

I would go into fuel pump till your sure that the problem.

I would invest in some new plugs and wires also first. IMO

 

[dna.od]

It does the same thing when in drive, but never enough to stall, nor does it ever stall when in idle. I just replaced the idle regulator solenoid couple days ago because the thing was running on and rattling for a couple minutes after I shut the engine off.

The stutter is just enough so I can feel it when under way. If I stomp on the pedal, it goes pretty good but not so I am assured it's not still stuttering.

I have made an appointment at two local repair shops for tomorrow morning. Hoped to have solve this myself but I should probably cut my losses and pay for an expert with some diagnostic equipment.

Thanks to everyone for the help.:worship:

 

[Ranger]

If I stomp on the pedal, it goes pretty good but not so I am assured it's not still stuttering.

That does not sound like a fuel pump. Have you checked the FPR?

 

[dna.od]

Hi Ranger:

I believe FPR means fuel pressure regulator. No I have not. Where is it? How do I check it? Or just replace it?

 

[dna.od]

Ranger, I read your post about the FPR. Found the item just to the driver's side of the throttle body. Pulled off the hose from the base of the TB to the FPR. STarted the engine. No fuel comes out. I wonder, if I run the vehicle w/o it? Does "no manifold pressure" to the FPR mean little or no fuel to the rail? Or the opposite?

 

[Ranger]

If you had no fuel to the rail, it would not run. The vacuum simply pulls on the diaphragm to open the return line valve. If it was not leaking, it's fine.