Cadillac

Cadillac Repair Questions? Ask a Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

Cadillac
This answer was rated:

I have a 1990 Cadillac Deville with the 4.5L V8 with 85K

Hello, I have a 1990...
Hello, I have a 1990 Cadillac Deville with the 4.5L V8 with 85K miles. It's have a rough idle as well as a shake felt through the steering wheel and gas pedal when under light load. If I stomp / chop on the gas, it smoothes out. When coasting, there's no shake. A mechanic told me that cyl#3 is misfiring. He went through the spark plugs, wires, and dist cap and had confidence that it wasn't an electrical issue. If I pull the plug wire off of cyl#3 at idle, it runs rougher, so she's firing, but maybe not always.Can the injectors have these issues of intermittent missing under different load ranges?
JA: How often does the vibration occur, and when did you last have the tires balanced?
Customer: Under light load only. It goes away if I power through it. I'm pretty sure that it's not unbalanced tires. It's dead-smooth while coasting. It will shake at any speed. It's only dependent on the engine rpm's and load.
JA: Are you fixing your DeVille yourself? What have you tried so far?
Customer: Mostly myself. I took it in to have the mechanic to look everything over (just bought it) and he told me to run Chevron Techron injector cleaner through it, only to make the issue a little worse. I've also replaced the in line fuel filter with no change and he had changed the plugs.
JA: Anything else you want the mechanic to know before I connect you?
Customer: If I'm cruising at 70mph, it gives me a rhythmic shake about every couple of second it shakes for about half a second, smoothes out, and shakes again, mile after mile.
Show More
Show Less
Ask Your Own Cadillac Question
Customer reply replied 6 months ago
I've been eyeing up some rebuilt 4-hole injectors on ebay for only $104 for all 8. I was just going to replace them all, hoping that will clear things up. I'm also contemplating buying a new fuel pressure regulator while I'm changing out the injectors since it will be easy to change at that time. Would either the injectors or FPR cause these issues?
Customer reply replied 6 months ago
Or could it possibly be something like the TPS or MAP sensors? Something possibly sticking when I accelerate slowly, but when I chop the throttle, something moves inside of the sensors and it can pickup on the input accurately?
Answered in 13 hours by:
6/9/2017
eric remington
Category: Cadillac
Satisfied Customers: 296
Experience: mechanic/service advisor at topline auto
Verified

H​ell there are several thing s that can cause a misfire......do you have acess to a vacuum gauge or scanner

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
I picked up a fuel rail pressure gage that I have yet to try. I don't have a scanner or a vacuum gage. It's not throwing any idiot lights. What were your thoughts if I were to rent one or both of those tools?

v​acuum gauge can tell you if you have mechanical problem or vacuum leak scanner can give other info....but ck engine vaccum it should be steady 18 inches. if its not steady what is it doing and where is it at?

Ask Your Own Cadillac Question

a​lso you can listen to the injector to see if it is engaging disengaging by a clicking sound....but that doesn't tell you if its clogged or unclogged...if your vacuum gauge reads low vacuum like 14 15 and it is oscillating extensively.....compression test...if vacuum gauge is rolling like 13 or 14 then up to 16 17 it is a vacuum leak and you must find it....scanner can give you codes....ohhhh I forgot you can access codes from the heating and Ac unit...ill show you how to do that but do these tests first

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
Do I check the vacuum off of the throttle body, the same port as where the FPR connects? Also,are we just talking about 18 while idling, steady throttle, or chopping? I'll need to remove a few things in order to get to the plugs to check the compression (kind of buried). I'll have to get back to you next week with the results.

w​ell if you have a smooth 18 inches no compression test necessary....you need a vacuum source where vacuum present at idle.....only if you get rapid oscillations.. turn key on and push off and warmer buttons on hvac unit key on engine off see if any codes pop up

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
Well I got around to testing the vacuum through the hose coming off of the TB for the FPR and she measured a fairly constant 17+/-1 in Hg. The needle would bounce rapidly but by only around +/-0.3 and 0.5 at its extremes. The vacuum pressure would go up to about 20 if I held the throttle steady, above idle (no idea RPM, manually operating throttle from engine bay).Then I tested the fuel pressure and it was at 41psi while engine off, key on. Over about 10-15mins of testing the static drop with engine off, it dropped from 41psi to 30psi. This seems a bit fast correct? Thinking fuel pump? I've just replaced the in line fuel filter with no change in performance and I would think that the car would run worse the harder I accelerate, not smooth out as it's doing.When idling, the fuel pressure stays steady around 36-38psi.

ok good swap injectors and or coils when you scan it and find out which cylinder is misfiring compression test?

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
I had it scanned at Orieley's through the OBD1 port today and nothing came up. That's what u mean by "scan" right? The only code that came up when I did the key on and pushed and held the off an warm buttons on the HVAC was a code F11 which looks like a problem with the upper A/C temp circuit. Nothing on my misfire issue, but any recommendations on the F11 code?

any problems with ac? what about misfire yu have misfire on no 3? correct? so have you done any diagnostic testing to locate that issue

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
Yup, A/C just blows hot air. I got a bottle of refrigerate recharge, thinking that it was just low, but turns out that the compressor never kicks on. If the F11 code says that there's a problem with the high-end circuit, does that mean that is a problem with one of the sensors on the A/C condenser canister? I saw a sensor or switch coming off the canister and another one mid-line.It's still doing its rough idle / rythmic shake misfiring. It's been spurattic though. It ran great for 5 mins on a drive last night, but then started acting up again.

o​k I would swap injectors and or coils for misfire...I'm really only supposed to address one issue but fr you I will look up that code and advise you

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
Understood. The A/C is much more of a back-burner issue. I will swap the injectors and let you know.Will I need any gaskets or new seals to swap the injectors? The new injectors already come with new orings, but I'm curious about gaskets for other components that I must move out of the way to get the rail free like the power steering pump or anything else?

If you take any power steering componenets loose change orings

Ask Your Own Cadillac Question
Customer reply replied 6 months ago
I was able to get the power steering assembly off to the side without disconnecting anything. Luckily the lines are JUST long enough to move the whole thing out of the way.Boy did I ever find out how many vacuum lines there are! Of coarse I snapped an elbow and there are some hoses that are very dry and in need of replacing.So now I've got everything out of the way, the fuel rail is loose, and I disconnected the gas lines and electrical harness. What's the best way to get the whole assembly out with all of the injectors pitched at different angles from eachother? Gingerly pull up on each injector at a time until the orings are out of each port and lift the entire assembly out?
Customer reply replied 6 months ago
Do you recommend any spray lube to help them pop out? They seemed a little stuck in there, but I didn't pull too hard. I didn't want to damage the rail at all and it's not the easiest to get a hold of the injector bodies with your hands...

I​f the only thing holding injector is an old oring you may have to put a little persuasion but I would soak it with some penetrating oil for a couple of hours

Ask Your Own Cadillac Question

so how is it going?

Ask Your Own Cadillac Question
Customer reply replied 5 months ago
Sprayed some penetrating oil and used a wide and dull chisel wrapped with a rag to pry up on the fuel rail by each injector.Ohm tested all of the injectors and found both cyl# ***** & 5 to be WAY out of spec!
#1 = 15.5
#2 = 12.8
#3 = 3.0
#4 = 14.5
#5 = 3.6
#6 = 15.4
#7 = 11.3
#8 = 10.8
All of the new injectors measure between 14.3 - 14.6. Very consistent....unlike the old ones. These new injectors don't quite seat as for into the fuel rail though, roughly 3mm less. Hopefully we don't have any leaks! I'm going to be installing it now.I've also gone and replaced the fuel pressure regulator while I have the rail off. Also replaced all of the old rubber vacuum lines. They were all cracked up once I touched them. Look fine from the outside, but the inside is cracked 3/4 through!

ok so replacing injectors is first step hopefully no damage to pcm as a result

Ask Your Own Cadillac Question

yes good job a vacuum leak can cause huge problems sounds like you are on track...so let me know if it runs good at that point or whether we need to do more...sometimes its a step by step process, till all problems are resolved

Ask Your Own Cadillac Question
Customer reply replied 5 months ago
Success!!! She's running nice and smooth, has much more get-up. No more shake under load. I'll keep an eye on the injectors for a leak, but it looks promising in the first few miles. Thanks for the help!

no problem that is why I am here and at least part of the reward is knowing that your issue s are resolved thanks for using just answer. please do rate me as my compensation depends on that

eric remington
Category: Cadillac
Satisfied Customers: 296
Experience: mechanic/service advisor at topline auto
Verified
eric remington and 87 other Cadillac Specialists are ready to help you
Ask your own question now
Ask eric remington Your Own Question
eric remington
eric remington
eric remington
Category: Cadillac
Satisfied Customers: 296
296 Satisfied Customers
Experience: mechanic/service advisor at topline auto

eric remington is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here.

DianeDallas, TX

< Previous | Next >

Meet the Experts:

Jerry Newton

Jerry Newton

Cadillac Technician

1,569 satisfied customers

ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.

Dave Nova

Dave Nova

Cadillac Technician

1,522 satisfied customers

ASE Master Certification. GM World Class Certification

Gm Tech (Cam)

Gm Tech (Cam)

Cadillac Mechanic

1,001 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

John

John

ASE Certified Technician

941 satisfied customers

ASE CERTIFICATIONS A1-A8 & L1 / 40 YEARS AUTOMOTIVE EXPERIENCE

George H.

George H.

ASE Certified Technician

775 satisfied customers

ASE Master Tech 15+ Years

Chris (aka- Moose)

Chris (aka- Moose)

Cadillac Technician

741 satisfied customers

16 years of experience

Don - Mo Lurch

Don - Mo Lurch

Cadillac Technician

690 satisfied customers

GM, Cadillac Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.

< Previous | Next >

Related Cadillac Questions
Gas is getting to fuel filter, ive replaced the fuel relay
gas is getting to fuel filter, ive replaced the fuel relay fuse and filter. the truck will start with ethenol, or starting fluid. but will not start with just gas … read more
roy
roy
Associate Degree
3 satisfied customers
Think I lost u. fuel pump replacement 97 Eldorado. mechanics
think I lost u. fuel pump replacement 97 Eldorado. mechanics quote: $700. Filter needs replacing too. … read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
How does it take to remove and replace the fuel pump on a
How long does it take to remove and replace the fuel pump on a 2006 Caddillac SRX v6 @ what rate per hour… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
Looking for the location of the high pressure fuel pump,
Looking for the location of the high pressure fuel pump, 2008 cadillac sts … read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
4,096 satisfied customers
Bad fuel pump for 1999 Cadillac Deville, need to to how
Bad fuel pump for 1999 Cadillac Deville, need to to how replace. … read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
Replacing fuel pump on 97 deville. hard to do? anyhting
replacing fuel pump on 97 deville. hard to do? anyhting special i need to know? … read more
3pac2222
3pac2222
nissan master auto tech
Associate Degree
2 satisfied customers
Voltage at fuel pump. Used pump. 01 devill. Used pump I only
voltage at fuel pump JA: Have you ever replaced the fuel pump, or is this the original? Customer: used pump JA: What is the model/year of your Cadillac? Customer: 01 devill JA: Are you fixing your veh… read more
fordguy4u
fordguy4u
Automotive Tech
Vocational, Technical or Trade Scho
70 satisfied customers
Replaced fuel pump at dealership, The same day I picked it
Replaced fuel pump at dealership, The same day I picked it up we went to lunch came out and the car would not start. Called the dealer they towed the car. They called today and said the fuse box with … read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
4,096 satisfied customers
2008 cadillac esv u code and blowin fuel pump control module
2008 cadillac esv u code and blowin fuel pump control module fuse … read more
Jerry Newton
Jerry Newton
Cadillac Technician
Vocational, Technical or Trade Scho
1,569 satisfied customers
I have a 1999 cadillac sts. A new fuel pump was put in.
I have a 1999 cadillac sts. A new fuel pump was put in. However, the engine starts, but it stalls after a few minutes. Why does it Stall? Could it be an electrical Problem? Where should I begin to che… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
Where is the fuel pump reset on a 2002 cadillac escalade, no
where is the fuel pump reset on a 2002 cadillac escalade … read more
Triston
Triston
High School or GED
1,134 satisfied customers
I had a low pressure fuel pump replaced in May 2017 on a
I had a low pressure fuel pump replaced in May 2017 on a 2011 SRX because the car stalled out at a stop light and would not restart. Code was P069E. They also replaced the fuel pump sensor and the bat… read more
Chris (aka- Moose)
Chris (aka- Moose)
Cadillac Technician
Vocational, Technical or Trade School
741 satisfied customers
I just changed the fuel filter on my 2009 cadillac sts, now
I just changed the fuel filter on my 2009 cadillac sts, now it won't start, it just clicks … read more
Mechanic01
Mechanic01
1,278 satisfied customers
I have removed the Ring retaining the fuel pump on my 2003
I have removed the Ring retaining the fuel pump on my 2003 Cadillac Deville but the pump will not pass through the tank portal, being slightly larger than the sleeve connected to the tank. Is that sle… read more
TIM MOHR
TIM MOHR
SHOP OWNER
Master's Degree
8,037 satisfied customers
I am getting a obo code of P069E for the fuel pump in my
I am getting a obo code of P069E for the fuel pump in my 2009 Cadillac Escalade hybrid. Check engine light came on. Sometimes there is a loss of power and when started it does not start easily. I'm tr… read more
TIM MOHR
TIM MOHR
SHOP OWNER
Master's Degree
8,037 satisfied customers
If my fuel pump is bad and I hammered the fuel tank while
If my fuel pump is bad and I hammered the fuel tank while trying to turn the car on will it turn on… read more
George H.
George H.
ASE Certified Technician
Associate Degree
775 satisfied customers
Need to change the fuel filter on my 2010 sex, not sure,
need to change the fuel filter on my 2010 sex JA: Is the fuel filter an external one, or is it inside the tank? Customer: not sure JA: What is the model of your '10 Cadillac? Customer: 2010 sex 3.0 JA… read more
Gunvir Singh
Gunvir Singh
1,796 satisfied customers
Replaced fuel pump and now car won't fire. This was the
Replaced fuel pump and now car won't fire JA: Have you ever replaced the fuel pump, or is this the original? Customer: This was the original JA: What is the model/year of your Cadillac? Customer: 1997… read more
DoctorD
DoctorD
Shop Owner
Vocational, Technical or Trade Scho
652 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x