Spark Plugs: What do YOU run?
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 1 of 5 1 2 3 4 5 LastLast
Results 1 to 15 of 63
HT4100 4.1, 4.5, 4.9 Discussion, Spark Plugs: What do YOU run? in Cadillac Engine Technical Discussion; I'm changing the plugs soon in my 4.5. I have an ACCEL super coil, MSD cap and rotor, and MSD ...
  1. #1
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Spark Plugs: What do YOU run?

    I'm changing the plugs soon in my 4.5. I have an ACCEL super coil, MSD cap and rotor, and MSD 8.5mm wires all feeding my current AutoLite double platinum plugs. They only have 20K miles on them but I'm having a 'stumbling upon acceleration' issue and I cant find anything wrong with the fuel system so now I'm on to the ignition....

    I'm not trying to start a 'my plugs are better than your plugs' debate. Im just curious what everyone is running in their 4.x and how satisfied are you with your choice of spark plugs?

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    74
    Posts
    41,617

    Re: Spark Plugs: What do YOU run?

    Take a hard look at NGK Iridium plugs.

    We run those in our heavy duty Olds 455 marine engines - not cheap but they stay clean and last forever.

    Stumble on acceleration is usually not spark plugs unless you have the coil wired backwards or the distributor module is on its last legs.

  4. #3
    drewsdeville's Avatar
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): none
    Join Date
    Oct 2004
    Location
    WI
    Posts
    5,235

    Re: Spark Plugs: What do YOU run?

    I'm not brand loyal as far as spark plugs. I never noticed performance differences between brands (except on two-strokes). I just replace the plugs with whatever type it came with using whatever brand is on sale at the time. I'm all about minimizing cost of ownership with my cars and I think being brand loyal can cost too much (especially when you keep multiple cars as long as I do!). Of course there are cases where I make exceptions and use only AC Delco. However, plugs aren't one of them.

    I'm pretty sure I have regular single tipped platinums in my 4.9...I think Bosch. They've been in there since the first month I've had the car, maybe 7-8 years. No problems.

    I can't remember what my '90 has anymore...but they both run perfect.

    I agree with Sub, put your concentration elsewhere.

    Little petty problems like this get especially hard to diagnose when things have been modified. If I remember your car correctly, you have Bosch injectors, deleted EGR, deleted AIR system, and an aftermarket ignition system...

    Sometimes you just have to let the problem get worse before you can accurately diagnose it. The problem will be annoying while it's there, but try to diagnose too early and you could end up sticking more time and money into it than the problem is really worth.

  5. #4
    quins90lac's Avatar
    quins90lac is offline Cadillac Owners Enthusiast
    Automobile(s): 1990 Cadillac sedan devile
    Join Date
    May 2008
    Location
    Peoria IL USA
    Age
    32
    Posts
    616

    Re: Spark Plugs: What do YOU run?

    just replaced mine with ac delco platinum's hope they last longer then my standard ac's they barely made it 3 years.

  6. #5
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by drewsdeville View Post
    I'm not brand loyal as far as spark plugs. I never noticed performance differences between brands (except on two-strokes). I just replace the plugs with whatever type it came with using whatever brand is on sale at the time. I'm all about minimizing cost of ownership with my cars and I think being brand loyal can cost too much (especially when you keep multiple cars as long as I do!). Of course there are cases where I make exceptions and use only AC Delco. However, plugs aren't one of them.

    I'm pretty sure I have regular single tipped platinums in my 4.9...I think Bosch. They've been in there since the first month I've had the car, maybe 7-8 years. No problems.

    I can't remember what my '90 has anymore...but they both run perfect.

    I agree with Sub, put your concentration elsewhere.

    Little petty problems like this get especially hard to diagnose when things have been modified. If I remember your car correctly, you have Bosch injectors, deleted EGR, deleted AIR system, and an aftermarket ignition system...

    Sometimes you just have to let the problem get worse before you can accurately diagnose it. The problem will be annoying while it's there, but try to diagnose too early and you could end up sticking more time and money into it than the problem is really worth.
    EGR is not deleted. I only do that when diagnosing a problem and want to rule it out. Timing is at 10deg.

    I recently compared the 'fuel used' on the DIC to the actual fuel used. I started with 17.3 gallons and drove until I had 3.5. That's 13.8 gallons but the DIC said 10.3. A difference of 3.5 gallons. Somehow fuel is getting into the engine unaccounted for. Problem is, when I pulled the rail up and turned the key on with 40+ psi to the rail there were no drips. I watched the guage slowly lose pressure while still observing no drips at all from the injector tips. According to the FSM the leakdown is at the fuel pump check ball... No leaky FPR either.

    I've done every fuel system test in the book and everything is in spec. Yes, the bosch injectors are .2lbs higher flow rate than oem but I had no issues when I first got them. It seems as if the engine gets choked off with fuel accelerating off-idle. Its even worse when cold which makes sense because the ecm is running the car richer until the engine reaches closed-loop.

    And another thing: When sitting at a light the integrator counts slowly reduce down from 128(ideal) all the way down to 89. A lower value means the computer is taking time off of the pulse width to get the air/fuel ratio where it should be. This further confirms rich operation which leads me to believe that this is what fouled up one of my o2 sensors in a previous thread.

    Everything points to leaking injectors but as I said, they did not leak before my eyes. And 3.5 gallons is ALOT of gas to have simply dripped away. PLUS: All the computer parameters that indicate rich operation are identical for both banks and stayed that way when I swapped the right injectors for the left 4. Its is inconceivable that ALL 8 injectors began to leak the same amount at the same time. Something is affecting the fuel system globally. Only the fuel pump, FPR, and the ECM can do that as far as I know.

    After all the testing and monitoring I've gone through I'm at the point where I'm ready to just start blindly throwing parts at it. The DIC says I'm getting 21.4 mpg but the actual mileage is really 16.5mpg. The car loses about 25% of its fuel per tank. SO I can keep wasting money on gas until something breaks all while running the risk of ruining another set of o2 sensors OR pretty much flip a coin and buy parts. Either way I lose.

    Even though the FPR does not viibly leak, and both static and dynamic pressure test indicate that it is ok, that's the first part I'm gonna try. I ordered the cheapest 'KEMPARTS' FPR from rockauto for under $30. If that doesnt change anything, I'll try another ECM followed by another set of injectors. No change after that and I'm getting a Honda.

  7. #6
    quins90lac's Avatar
    quins90lac is offline Cadillac Owners Enthusiast
    Automobile(s): 1990 Cadillac sedan devile
    Join Date
    May 2008
    Location
    Peoria IL USA
    Age
    32
    Posts
    616

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by Sevillian273 View Post
    EGR is not deleted. I only do that when diagnosing a problem and want to rule it out. Timing is at 10deg.

    I recently compared the 'fuel used' on the DIC to the actual fuel used. I started with 17.3 gallons and drove until I had 3.5. That's 13.8 gallons but the DIC said 10.3. A difference of 3.5 gallons. Somehow fuel is getting into the engine unaccounted for. Problem is, when I pulled the rail up and turned the key on with 40+ psi to the rail there were no drips. I watched the guage slowly lose pressure while still observing no drips at all from the injector tips. According to the FSM the leakdown is at the fuel pump check ball... No leaky FPR either.

    I've done every fuel system test in the book and everything is in spec. Yes, the bosch injectors are .2lbs higher flow rate than oem but I had no issues when I first got them. It seems as if the engine gets choked off with fuel accelerating off-idle. Its even worse when cold which makes sense because the ecm is running the car richer until the engine reaches closed-loop.

    And another thing: When sitting at a light the integrator counts slowly reduce down from 128(ideal) all the way down to 89. A lower value means the computer is taking time off of the pulse width to get the air/fuel ratio where it should be. This further confirms rich operation which leads me to believe that this is what fouled up one of my o2 sensors in a previous thread.

    Everything points to leaking injectors but as I said, they did not leak before my eyes. And 3.5 gallons is ALOT of gas to have simply dripped away. PLUS: All the computer parameters that indicate rich operation are identical for both banks and stayed that way when I swapped the right injectors for the left 4. Its is inconceivable that ALL 8 injectors began to leak the same amount at the same time. Something is affecting the fuel system globally. Only the fuel pump, FPR, and the ECM can do that as far as I know.

    After all the testing and monitoring I've gone through I'm at the point where I'm ready to just start blindly throwing parts at it. The DIC says I'm getting 21.4 mpg but the actual mileage is really 16.5mpg. The car loses about 25% of its fuel per tank. SO I can keep wasting money on gas until something breaks all while running the risk of ruining another set of o2 sensors OR pretty much flip a coin and buy parts. Either way I lose.
    sounds about like the problem im haveing right now . just replaced the plugs, wires, cap, rottor and module. Then reset my timing to 11 btdc .now in the morning when i go to start it it wont start some times untill i crank it about 4-5 mins .got codes checked every thing and it's right. I even re adjusted the ISC and eh TPS and replaced the O2 and yet i contunes to do the same thing.

    Also got the same fuel problem you do but really haven't gotten on checking every thing. Changing the FPR was enough of a PITA the first time i did it not in a rush to do again

  8. #7
    drewsdeville's Avatar
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): none
    Join Date
    Oct 2004
    Location
    WI
    Posts
    5,235

    Re: Spark Plugs: What do YOU run?

    I don't know how to help you with your problem from behind the keyboard, but keep in mind that the ECM uses the coolant temp and MAP sensor signals as coarse adjustment for the fuel system, so be sure that those are in spec.

    Hows your fuel mileage, calculated, not from the DIC?

  9. #8
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by drewsdeville View Post
    I don't know how to help you with your problem from behind the keyboard, but keep in mind that the ECM uses the coolant temp and MAP sensor signals as coarse adjustment for the fuel system, so be sure that those are in spec.

    Hows your fuel mileage, calculated, not from the DIC?
    The calculated fuel mileage is 16.5mpg although the DIC reads 21.4mpg.

    IATS, MAP, and ECTS all test good. ECTS is brand new and IATS will be replaced shortly. In fact EVERYTHING tests good. The previous owners are deceased so I have to wonder if this car is haunted.

  10. #9
    jzchen is offline Cadillac Owners Fanatic
    Automobile(s): '85 Sedan de Ville, '10 CTS-V
    Join Date
    Sep 2009
    Location
    Arcadia, CA
    Age
    38
    Posts
    295

    Re: Spark Plugs: What do YOU run?

    I used Bosch Platinum +4 before the accident. The car ran great with them.

  11. #10
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by jzchen View Post
    I used Bosch Platinum +4 before the accident. The car ran great with them.
    Wow thats a rare thing to hear! Most forums frown upon those plugs but I've never seen any real evidence as to why they 'are no good'. Most praise AC Delcos as gospel and conversely I haven't seen any evidence as to why.... But I do think that recommendations come from real experience and that is tangible enough for me so when I'm done blindly throwing parts at the fuel system, my next set will be Delcos. Changing plugs on a transverse V8 is no fun otherwise I'd take my chances with the +4's but I've heard alot more negative rhetoric about them than positive... Whether it be fuel or spark, I still feel I'm in a no-win situation.

    And to add insult to injury, my latest calculation on my most recent tank of gas has revealed 14.4 mpg while the DIC says 21.1mpg...

  12. #11
    drewsdeville's Avatar
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): none
    Join Date
    Oct 2004
    Location
    WI
    Posts
    5,235

    Re: Spark Plugs: What do YOU run?

    Sorry, I'm out of ideas on this one. You can try plugs but I doubt those will help any. If the plugs were bad enough to return you 14.4mpg, that thing would be chugging and misfiring so bad...

    Let me ask you this, are you sure of the non-stock injectors you have installed? Did you physically check the number stamped on them to ensure they are the "correct" 19# ones?

  13. #12
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by drewsdeville View Post
    Let me ask you this, are you sure of the non-stock injectors you have installed? Did you physically check the number stamped on them to ensure they are the "correct" 19# ones?
    What resource could I use to check them? And it ran good and got normal mileage for a few months after I installed them. The driveability problem gradually set in along with the bad mileage.

    I got my $30 FPR in the mail (looks like the $50 BWD unit that you recommended) so I'll put that in. After all, the rubber diaphragm inside IS 20 years old and I'm sure the rubber compound wasn't designed for 10% ethanol... I doubt this will fix the problem. This is becoming more and more like like the madness I went through with code E041 which turned out to be the ECM after hours and hours of diagnostic work and parts. I hate to do it, but I'm gonna drop another $80 on a ECM if the FPR has no effect. After that, I'm gonna sell all of my tools, lease a Yaris, and get a desk job.

  14. #13
    ehall's Avatar
    ehall is offline Cadillac Owners Connoisseur
    Automobile(s): 1985 Sedan DeVille
    Join Date
    Aug 2007
    Location
    Southern Maryland
    Posts
    1,487

    Re: Spark Plugs: What do YOU run?

    I have the Accel plugs and 8.8 wire, my tires were chirping when I had it fresh installed

    Stumble on tip-in is usually EGR. Plug off the vacuum line from the valve to the solenoid and see if the problem goes away.

  15. #14
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by ehall View Post
    I have the Accel plugs and 8.8 wire, my tires were chirping when I had it fresh installed

    Stumble on tip-in is usually EGR. Plug off the vacuum line from the valve to the solenoid and see if the problem goes away.
    Done - no dice. I even removed the valve and blocked the passage with a plate to rule it out completely. All it got me was a E048 and a light knock at cruise.

    I need a way to SAFELY monitor fuel pressure while driving at any speed. My guage is to short to reach the windshield. Cant seem to find an extension for it.... I'd rather not hack the hose. Fire sucks.

  16. #15
    drewsdeville's Avatar
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): none
    Join Date
    Oct 2004
    Location
    WI
    Posts
    5,235

    Re: Spark Plugs: What do YOU run?

    Quote Originally Posted by Sevillian273 View Post
    What resource could I use to check them? And it ran good and got normal mileage for a few months after I installed them. The driveability problem gradually set in along with the bad mileage.
    Well, I'd say that pretty much rules that out then.

    Like ehall stated, the stumble and the mpg issue are EGR symptoms and the OBD1 system CEL's aren't exactly a reliable indicator of proper EGR operation. These engines use a positive back pressure type EGR valve, so testing the EGR will require you to create backpressure to raise the lower diaphragm to test if the upper diaphragm will hold vacuum. You'll also need to check for proper EGR controller operation. I'm sure your FSM has the info on that.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting