Tune up time?

After searching I didn't find a clear cut answer to my question so I apologize if it is redundant.
My car runs great accelerates & idles fine w/ 75k. I am hoping plugs & wires will fix the 30-40 mph lag after downshifting. I can only assume they are original. Any advice or suggestions is always appreciated.

Magnecor Electrosports-70 (7mm) Ignition Cables
Part# 67207
AC Delco 41-101 iridium plugs which don't need to be gapped?

carguy8888 wrote:

After searching I didn't find a clear cut answer to my question so I apologize if it is redundant.
My car runs great accelerates & idles fine w/ 75k. I am hoping plugs & wires will fix the 30-40 mph lag after downshifting. I can only assume they are original. Any advice or suggestions is always appreciated.

Magnecor Electrosports-70 (7mm) Ignition Cables
Part# 67207
AC Delco 41-101 iridium plugs which don't need to be gapped?

Word to the wise: Magnecor cables are quite good, but in my case they chose not to honor their warranty. When I returned the cables for inspection there was a small amount of underhood grime on them and I was told they were rejected on that basis. Problem is, that had nothing to do with the problem I had - my problem was that the coil-end terminal had ablated in use.  I asked for the cables back and offered to pay return shipping, but Magnecor did not return the cables to me. I surmise this was because the original owner was in process of selling the company, and my guess is he pitched them.  So... if you're deciding to buy the cables, if I were you I would ignore the warranty in weighing your decision. And if one of you reading this is affiliated with Magnecor, I'm still open to discuss/resolve this problem, it's only business.  

With the Delco plugs, be sure to measure the gap anyway.  Sometimes in shipping. stocking or other movement the little boxes get dropped and the cathode tang gets bent in.  If that happens, the point would be to use a proper plug caliper or a Snap-On CF-72/equivalent and not a gauge with a bit or hole. You don't want to touch the anode at all when gapping these things. Best move would be to get them from a parts store and just check the gap at purchase -- keep the counter person checking them until you get 6 that are correct.

Is this the combo you suggest? I will not be doing it myself.

carguy8888 wrote:

Is this the combo you suggest? I will not be doing it myself.

This combo is OK.

A combo with Delco wires is OK.

In my personal experience, Champion Iridium plugs are OK too, I have used both and would use either one. I admit that I liked the Champions a little more than the Delcos. My next change, I will use Champions most likely.

The NGK 5599 plugs that look like the Delcos... well, I was told NGK was the OE, so they should be the same plug.

carguy8888 wrote:

After searching I didn't find a clear cut answer to my question so I apologize if it is redundant.
My car runs great accelerates & idles fine w/ 75k. I am hoping plugs & wires will fix the 30-40 mph lag after downshifting. I can only assume they are original. Any advice or suggestions is always appreciated.

Magnecor Electrosports-70 (7mm) Ignition Cables
Part# 67207
AC Delco 41-101 iridium plugs which don't need to be gapped?

30-40 MPH lag?  What does that mean?

IMO, there is absolutely no reason not to use the OEM Delco wires.  I think they are that good, and inexpensive.

Yes, check the gap. It's usually fine. The AC Delco and NGK Iridiums are identical. Get the ones that are cheaper.

Thank you both. I got the lag terminology from searching here. If I'm doing between 30 and 40 miles an hour and I accelerate using medium throttle the car bogs or hesitates for roughly two seconds before it takes off. The SES light is off and there are no codes. This is why I was considering the tune-up.

The torque converter may be locked up in 3rd gear. It should unlock with enough throttle, maybe it isn't. I don't think the tune up will help.

I had the third gear lockup removed by John@intense racing.

carguy8888 wrote:

I had the third gear lockup removed by John@intense racing.

You have something else going on then. Do you have a boost gauge?

I don't unless I could find one on the torque app or you can suggest me doing something. It's done this since I bought the car and before and after the tune, I thought it was an inherent problem with this platform? Maybe what you're saying makes sense, I can try leaving the car in third and see if it does it. Maybe it is going from 4th in lock up and that's where I'm having a problem?

There is a Boost Bypass valve that is controlled by a solenoid and canister. You may not be getting full boost, or it may be the boost is delayed. Read this thread,

https://rivperformance.editboard.com/t2083-faq-boost-bypass-valve-boost-control-solenoid-questions-no-boost?highlight=Boost+bypass+valve

That's why I asked if you had a boost gauge. They are very easy to install.

I have over 200K on my engine. It is responsive everywhere.

Wow, thank you Larry. For a 20 year old $30 part I will probably just have my guy change it, check the T connector and the lines. My car is also very responsive everywhere except for that 2 second delay and I do hear the sc whine. But after reading that doesn't mean the bbv is doing it's job. Looking forward to see if it makes a difference.

2 seconds is a lot.  My converter unlocks very easily.  In overdrive on the highway, it doesn't take much throttle to unlock it and down shift to 3rd. The car just flies, it is surprisingly quick.


When spark plugs and wires need changing, you will get misfires. That's hard to mistake for anything else. I would hold off on the tune up.

On the highway it kicks down quickly, just seems to be that 30-40 spot. Off tomorrow and going for an oil change so I hope they find a problem. My car has no codes and runs too good otherwise to be misfiring. It certainly would be nice to find it was only running on part boost. Thanks for pinpointing the difference between this issue and the tune up.

LARRY70GS wrote:

carguy8888 wrote:

After searching I didn't find a clear cut answer to my question so I apologize if it is redundant.
My car runs great accelerates & idles fine w/ 75k. I am hoping plugs & wires will fix the 30-40 mph lag after downshifting. I can only assume they are original. Any advice or suggestions is always appreciated.

Magnecor Electrosports-70 (7mm) Ignition Cables
Part# 67207
AC Delco 41-101 iridium plugs which don't need to be gapped?

30-40 MPH lag?  What does that mean?

IMO, there is absolutely no reason not to use the OEM Delco wires.  I think they are that good, and inexpensive.

Yes, check the gap.  It's usually fine.  The AC Delco and NGK Iridiums are identical.  Get the ones that are cheaper.

A few semi-random comments:

1) My car used to bog between 50-60 MPH accelerating in 3rd.  Replacing the OE exhaust unexpectedly fixed that - first the custom SS and 3" downpipe from NeverRust that I put on, then the 2005 Park Avenue exhaust, which could be aptly named "silent but deadly."

2) Some people get a lot of mileage out of the Delco wires without incident.  My first set I got about 40K, the second set about 90K.  Again, the Delco wires are OK. I just pulled a set of them last year after running them a couple years.  ATM I am using a set of Belden 700951 wires that I got on closeout from rockauto.com -- turns out they are what were NAPA's top of the line wires in beat-up NAPA boxes.  Which worked for me, I'm running the wires not the boxes...   I think they're the same as the Standard Premium 7671 wires.  Another good bet would be the Denso 6716052.  Prestolite 116054 are the same, I am told, among the Rockauto closeouts.  

3) If you are having an ignition problem on these cars, look at the coils as well as the wires.  Use a multimeter to check the coil resistances.  Point one is all the primaries and all the secondaries should match each other.  Point two is, elsewhere on this site the resistances for the Delco D576 coils is listed.  If your coils do not match those specs, your best best is to get a set of them that do.  BY THE WAY the other coils on the RockAuto site listed for the SC Riv are not the SC coils.  ONLY the D576 or equivalent.  The other ones will work until you are trying to drive the car kinda hard.  Anyway - an inexpensive way to do that is pull them off a junkyard car that has the SC 3800 Series II engine - I have seen many more Grand Prix GTP, Park Avenue  or high spec Regal than Riviera and suspect it won't be tough for you to get such coils.  As for the spec I don't have it handy but I think it's in one of the Ignition posts or FAQs - please search on this site. I do remember that the primaries on these D576 coils runs 0.5 ohms (yes that's right, half an ohm).  What you are looking for is shorts to ground or leakage between primary and secondary.  This is a very quick check.    While we are on the topic, you might find this entertaining: https://www.youtube.com/watch?v=THJjLuWTi4c

Albert,
Thank you for all the great information. I'm pretty sure I do not have a miss and I'm going to do the tune-up but first check out the sc valve.

Whelp, boost bypass valve certainly looks like it is working properly. My guy didn't have a vacuum gauge but when I started the car it moved and when we snapped the throttle it moved a lot and freely. Anything else I can check? Is it possible He suggested maybe I have some garbage in the fuel injection system. It's definitely not missing and super responsive except for this one spot.

You can check the throttle position sensor. If you have a scan tool that can read operational sensor data, you can slowly open the throttle to full (engine off, key on). Closed throttle should be .40 volts, and it should increase in a linear fashion to about 4.5 volts at full throttle. If you see a point at part throttle that jumps around in voltage, that might be the problem. All the sensors in the engine get a 5.0 volt reference voltage, and they return a signal voltage to the PCM. If you don't have a scan tool, you can back probe the TPS wires with a voltmeter. There are 3 wires, reference, signal, and ground. Check the FSM to see which is which.

Can a throttle position sensor work and have a dead spot?

carguy8888 wrote:

Can a throttle position sensor work and have a dead spot?

Yes, that's what I am saying. That is what happens when they fail.  I am trying to come up with things to check as I can't drive your car.

I'll have my guy check it next weekend, it does make sense. if that doesn't work I'm going to come over the Throgs neck or the Whitestone and you can drive it LOL.

LOL, OK

I watched a few YouTube videos and after seeing the part if you touch the two wires together you can fry the computer, that was non a chance I wanted to take. So, I had a new ACDelco TPS sensor installed. I will test it over the weekend when the roads dry out. Thanks Larry.

carguy8888 wrote:

I watched a few YouTube videos and after seeing the part if you touch the two wires together you can fry the computer, that was non a chance I wanted to take. So, I had a new ACDelco TPS sensor installed. I will test it over the weekend when the roads dry out. Thanks Larry.

The problem is that there is a difference between a mechanic and a parts changer.  A mechanic tests a part and replaces it if necessary, the parts changer just replaces parts.  Guess who spends more money and is more frustrated. I don't know if the TPS is your problem, I was just throwing things out there. I guess we will find out the expensive way.