G.T. Fieros

I just did an E-Test this morning and noticed the results were way off from 2 years ago.

It is an 88 with a 3800SC2 swap. Any ideas? Nothing has been changed between the tests.

The difference in the limits is because in 2012 it was tested as stock, and 2014 is was tested with hot rod status.



Thanks!

Hot Rod status has higher ratings since there wasn't much of an emission standard in 1980 yet. Your results might be higher because your dilution is lower. Not really sure but I believe the lower the dilution the leaner the car is running. How many km's you have on the current spark plugs & O2 sensor? Are you running stock iridium's or copper plugs? My 3400 motor went 100,000km+ on the stock iridium plugs but when I modified the motor, the replacement plugs only went 50,000 km approximately. Did some research this past weekend on iridium plugs, found out they run hotter then copper, last a lot longer but are not really meant for modified engines. My car just started missing on a couple of cylinders for some reason three weeks ago. I changed the wires and helped a bit (had one bad wire). I put new A/C Delco copper plugs in and runs just fine now.

I've noticed it's using a lot more gas too. I haven't changed anything but the oil since I bought it, 4+ years ago. I gues its time for a tune up. Will diagnostics show if it's the O2 sensor? It has a 96 grand prix gtp ecu. Less than 10k since I bought it, not sure how much was on them before.

1996 GTP ECU? are you running the 3.4L DOHC? You probably have a 97 PCM, first year the Grand Prix's came with the 3800 S/C. Good to do a tune up, just start with plugs and wires and see how she runs after that, don't want to change too many things at once. The OBD2 reader will show you what the O2 sensor is reading but unless you know what the values should be at optimal operation, it will mean nothing. May get some indication if you're running rich or lean. If you do decide to change the O2, put another A/C Delco back in, I've tried other brands on my GTP and would only pass emissions with Delco's.

If it is a 96 PCM you must be either manual tranny or have the 4T60E tranny which is not the best PCM to have but can be tuned and must be out of a Bonneville or other H body car.

Not sure on the ECU. I think that's what the previous owner told me.

Darn cars, it's manual, and swap was completed by you years ago I was told.

Black 88 GT with long tube headers. I'm sure you've done way too many to remember though.

I guess I'll start with the tune up, and move on from there...

thanks!

Black 88 GT with west coats Fiero headers, does it also have white faced gauges and real nice rims on it, if so it must be Angelo's old car out of Whitby. Then it would most likely be a 99 PCM and a tune up would not hurt as I built that one about 6 or 7 years ago. Dan

That would be the one! Thanks for the info.

If I look I should be able to find some photos of your car during the swap i can email them to you if you want them

That was Angelo's wife's car. Met him a few times, didn't take the car out much. I bought his old Centerforce which he first tried on the motor. Wouldn't hold up to the 3800, but no problem with my 3400 at the time.

That explains the "Karen's 88GT' inscribed on my speedometer. lol

Was supposed to be his wife's car but he never really got around to letting her drive it.

No worries, we'll just call you Karen from now on

Late to the party here, but looking at those numbers and you're comment about it drinking more fuel it sounds as if the stock O2 sensor may have seen better days, your HC(ppm) count is higher which tells me that its getting more fuel than it needs.

Granted there are many things that can cause a '99 3800SC to drink more fuel, personally I'd start with my aeroforce interceptor, read the maf sensor and O2 sensor readings, cause in my experience those two have been the cause of many fueling issues. Doesn't hurt to clean the MAF sensor and intake, probably want to look at the plugs and replace them if need be. Problem with the O2 sensor is if you don't have a scanner, narrow band O2 sensor gauge or bare minimum an old school sweeping voltmeter you won't be able to tell if the sensor is gone.

Still though, my money is on the O2 sensor, its probably worn/dirty/destroyed and its not reading proper and the computer is dumping mass amount of fuel into the engine.

Jer

So you are running hot and rich.

If I had to guess I'd say that you had a combination problem. Even if you put a real-time scanner on the O2 you still don't know if it's reading right only that it's reading. It could be reading an average of 5v (which is what you want) but it may no longer be calibrated properly so that won't tell you much unless you can get a second properly calibrated sensor in there at the same time to verify the operation.

You could be running hot because of old coolant, or insufficient cooling otherwise.

It could also be caused by an improperly operating EGR valve. If the valve has buildup changing the size of the orifices it could cause you to burn more fuel and stop the valve from closing all the way. You can try removing it and cleaning the generals and valve its-self (look online how to do it, it's kind of easy).

I'd say if you don't have the equipment to do the proper testing that you should clean you EGR system, put stock plugs back in and change the O2 sensors. Also it doesn't hurt to run an oil catch can (a good one! I wan't able to find one on-line so I'm making my own).

My car runs lower emission and it doesn't have a CAT.

Aaron

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