1999 GTS - Exhaust Manifolds Glowing Red

[emjohn43]

I know, I know...Vipers are hot. But this seems very very hot.

The car: 1999 GT-S, 9500 miles. No cats, rear muffler delete. Recently cleaned (RC Fuel Injection) injectors; after cleaning, all came back with a good bill of health. 100% OEM tune on the PCM.

If I start the car, let it idle for 5 minutes (or longer), the headers are already glowing red. I would understand if they were glowing after the car was just run through the gears, but literally not touching the gas on a cold-start idle for 5 minutes....seems off to me.

O2 sensors? Intake manifold gasket? Or just straight....normal?

 

[GTS Dean]

O2s are first check for proper function. Also check OBD tables for extreme adaptive trim settings. Maybe your mufflers are plugging up. Also keep in mind that the later Gen 2's came with thin-wall tubular steel headers instead of cast iron and it may not be uncommon for them to glow at idle. I just don't have experience with them.

 

[99RT10GTS]

It sounds like cats!!! Or as Dean said, mufflers. Go straight pipe or your injectors are ******. I have a set just cleaned and check for sale

 

[efnfast]

If you don't have cats/mufflers it's most likely unburnt fuel in the exhaust, either too rich or timing is too r-e-t-a-r-d-e-d. Checks O2s are working and what the fuel trims are as a starting point.

 

[TEALLIFE]

Id figure out why the fuel mixture is that far off at idle asap before running it anymore.. O2s, stuck injector...

Check the temps on each of the runners coming off the head to see if one isnt firing and dumping fuel.

 

[emjohn43]

Thanks guys!

Injectors have a clean bill of health from RC Injection.

No cats.

New O2 sensors have been ordered. They didn't appear laggy on the log, but for the cost, they're cheap to replace...and they're presumably 26 years old anyhow.

Both the short and long term fuel trims were near zero ...but the PCM has only about 7-8 minutes of run (idle) time on it since it was reflashed to stock (unsure if prior owner had a tune, cursory glances showed minor differences from other supposed OEM tunes of the same year and P/N, so I had the PCM reflashed to OEM).

I do have a Corsa exhaust order (ordered in December, hopefully it ships in March). Perhaps the center resonators are plugged up. That would make a lot of sense!

It's winter here, so car is not going anywhere, only future running would be idling in the garage to see if the new O2 sensors make a difference.

Will update once they're installed.

Thanks all!

 

[daveg]

STFT being near Zero is a good start even though the car hasn't run long enough for the STFT to reflect in the LTFT.

 

[GTS Dean]

On a reflash, your adaptives are all zero'd out. They won't move appreciably without driving some miles unless something is seriously out of whack.

 

[TEALLIFE]

Any chance the reflash was incorrect? I had this happen on another car when they put it back to "stock"

 

[steve e]

There is no way the stock resonators are clogged, they are nothing more than a straight pipe with small slits in the straight pipe with a chamber around it to soak up some noise, they do not restrict exhaust flow at all, the first thing I would check is the reflash and make sure all the pins in the connector are straight and clean

 

[Dyno Dave]

I would suspect the reflash but it sure is an odd set of circumstances. I used to retard the ignition timing to get those glowing header photos in the Viper brochures. Are both headers glowing red?

 

[emjohn43]

Both headers are glowing red, and they do appear to be glowing pretty evenly between banks.

I don't think it is the reflash, for two reasons. One, this happened before the reflash...and was one of the reasons for the reflash, and Two, the reflash was performed by a very reputable company that specializes in Vipers.

 

[efnfast]

If it was doing it before, and it's both banks, that really starts to sound like an ignition timing issue. I assume you didn't screw with the timing in the tune, so I wonder if maybe crank or cam sensor is doing it?

I once had an LS3 with ITBs ... to get it to idle we basically had to pull out all timing, which meant the headers got cherry red within 2-3 minutes of a stone cold start.

 

[emjohn43]

The timing questions got me thinking - I can log timing advance with the HP Tuners device.

Plugged it in, turned on the log, and started it up from a cold (60F) start in my garage.

Timing advance bounced between 0-deg and 4deg. The knock r-e-t-a-r-d was bouncing from 7.5-deg to 120-deg constantly. Even before the car was turned on. The bounce happened after turning it on too.

The fuel trims were different too. The short terms were about +12%, while the long term was about -3% and - 10% for bank 1 and 2, respectively.

I've got the O2 sensors on order, will install when they arrive. Does the Gen II car have a knock sensor? Or is it just cam & crank sensors?

 

[white out]

That sounds like a bad sensor.
Were your injectors bench flowed/tested?

 

[emjohn43]

The injectors were cleaned and flow tested by RC Injectors - I can upload the printout this evening, but they did need cleaned...and all came back with a good bill of health, good pattern, and flow numbers all within a few cc/min of each other.

 

[white out]

I'm betting it's a sensor issue then.

 

[TEALLIFE]

I'm betting it's a sensor issue then.

yup, easiest place to start.

 

[emjohn43]

I went to look at crankshaft position sensors, and stumbled onto a ton of drama and discontinued parts!

Seriously though, I did order a crank position sensor as well as a camshaft position sensor, and while expensive, are still quite a bit cheaper than sensors on German cars can be (even when in production), so we'll see. I won't be able to install them for a week - 10 days after they arrive, so it will be a bit before I can update here.

 

[Viper Specialty]

Few points:

-We did the reflash, thats not it. LOL

-Header glow is normal, however this seems excessive. Generally a dimly lit room is needed to see the glow.

-Before going crazy replacing parts, check what you currently have.

-Injectors are suspect. Cant hurt to have the double-checked.

-Gen-2 does not have Knock sensors.

-Check that all available sensor PID's match reality under cold and hot conditions.

-Idle control should have timing jumping around in order to keep idle speed. If it is static, that is suspect of an idle control window issue.

-Check O2 Heater function. Cold sensors will bias lean and dump fuel to compensate.

-Exhaust manifold leaks & cracks will bias lean, and dump fuel to compensate.

I cant stress enough. DO NOT *****-nilly start replacing parts with no direction. Thats how you accidentally introduce new problems and/or waste money.

W*I*L*L*Y is censored? Are you ******** me?

 

[Goggles Pizano]

Free w i l l y!

 

[Dyno Dave]

Here is the base spark for a 98 coupe and idle speed is 700 rpm. I would think a 99 coupe would be similar but I did not spend a lot of time looking for the 99 version.
The left column is rpm and base spark for the 704 rpm line is 10.000 degrees. The columns are divided by map. Idle would typically fall in around the 4th column.
I would think the 4 degrees you report is ******** from where it should be. I know DCFC (dynamic crankshaft fluctuation control) timing is active but still should be close to the specified timing.

I am not sure why you are seeing that. Has the engine ever had any internal work?

81 608. | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 |
81
81 704. | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.500 |
81
81 800. | 14.000 | 14.000 | 14.000 | 16.000 | 16.000 | 16.000 | 16.000 | 15.000 | 8.000 |
81
81 896. | 16.000 | 16.000 | 16.000 | 25.000 | 25.000 | 25.000 | 24.000 | 15.000 | 10.000 |
81
81 992. | 16.000 | 16.000 | 16.000 | 25.000 | 32.000 | 32.000 | 28.000 | 19.000 | 6.000 |

 

[Viper Specialty]

Here is the base spark for a 98 coupe and idle speed is 700 rpm. I would think a 99 coupe would be similar but I did not spend a lot of time looking for the 99 version.
The left column is rpm and base spark for the 704 rpm line is 10.000 degrees. The columns are divided by map. Idle would typically fall in around the 4th column.
I would think the 4 degrees you report is ******** from where it should be. I know DCFC (dynamic crankshaft fluctuation control) timing is active but still should be close to the specified timing.

I am not sure why you are seeing that. Has the engine ever had any internal work?

81 608. | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 |
81
81 704. | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.000 | 10.500 |
81
81 800. | 14.000 | 14.000 | 14.000 | 16.000 | 16.000 | 16.000 | 16.000 | 15.000 | 8.000 |
81
81 896. | 16.000 | 16.000 | 16.000 | 25.000 | 25.000 | 25.000 | 24.000 | 15.000 | 10.000 |
81
81 992. | 16.000 | 16.000 | 16.000 | 25.000 | 32.000 | 32.000 | 28.000 | 19.000 | 6.000 |

Idle control timing can fluctuate +/- 20 on a good day, not to mention all of the temp based multipliers and adders. Figuring base timing from total timing is nearly impossible unless you turn idle control off and have all of the temp based adders available to reference. I would be looking more for a "static" number opposed to a fluctuating number [on a total timing PID] as an indicator of a problem, because it should actually be fluctuating.

 

[Dyno Dave]

Idle control timing can fluctuate +/- 20 on a good day, not to mention all of the temp based multipliers and adders. Figuring base timing from total timing is nearly impossible unless you turn idle control off and have all of the temp based adders available to reference. I would be looking more for a "static" number opposed to a fluctuating number [on a total timing PID] as an indicator of a problem, because it should actually be fluctuating.

I would just interrogate the spkadv address and it gives the delivered spark with all multipliers and adders.

 

[Viper Specialty]

I would just interrogate the spkadv address and it gives the delivered spark with all multipliers and adders.

Yes... but idle timing control is going to poison that well, if its active.

 

[emjohn43]

You guys are way smarter than me on this - but I could, I think, get a log off my hpt dongle and upload via youtube.

Timing advance, o2 sensor voltage, and what else? It won't be until Sunday, but I could do that.

There has been no internal engine work that I'm aware of. I have all the records (I believe) from both the first and second owner; unless they kept records on wiper blades and trashed the internal engine work reciept; I don't think any was performed.

Thanks!

 

[Viper Specialty]

You guys are way smarter than me on this - but I could, I think, get a log off my hpt dongle and upload via youtube.

Timing advance, o2 sensor voltage, and what else? It won't be until Sunday, but I could do that.

There has been no internal engine work that I'm aware of. I have all the records (I believe) from both the first and second owner; unless they kept records on wiper blades and trashed the internal engine work reciept; I don't think any was performed.

Thanks!

To diag this, you really need a DRB-3, not HPT.