It's not really a concern, everything else about it is fine so who cares. It feels like my 3800 shakes the whole damn car and puffs out of the exhaust while idling. You get a nice smooth tone with just a *pum* every couple seconds, like a misfire that only exists at idle. Looking at misfire counts says everything is a-ok, so is that just what a 3800 sounds like and does? Everywhere else in the rev range it's plenty smooth and doesn't stutter... I know it's an inherently unbalance engine but this seems excessive.
My 3800SC idles smoothly. I would suggest doing a scan to determine if there is a problem . You can purchase a quality scanner at a good cost these days and they are easy to use..
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
My 3800SC Fiero idles smoothly at 1100 when first started cold and 850 when warm. Mine is not as quiet as Jelly's car, but not the loudest 3800SC i have heard either.
Last winter we determined that my throttle body was NOT the one from a 2002GTP, but one from an earlier SC and hence the MAF sensor was different. It was either change the TB or reprogram the computer, so i changed the TB.
i agree that a good scan will help isolate the problem.
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!
My 3800SC idles smoothly. I would suggest doing a scan to determine if there is a problem . You can purchase a quality scanner at a good cost these days and they are easy to use..
I've used the fancy ass Autel scanner at work, and it doesn't raise any red flags. I'm not sure if that's due to the tune from Sinister shutting off certain monitors so that I wouldn't have to do a CASE learn or what
I've used the fancy ass Autel scanner at work, and it doesn't raise any red flags. I'm not sure if that's due to the tune from Sinister shutting off certain monitors so that I wouldn't have to do a CASE learn or what
Yep if you had Ryan to turn those monitors off it will not report misfires.
Yep if you had Ryan to turn those monitors off it will not report misfires.
welp. I've replaced LIM, ICM, coils, plugs, and wires. I've got good fuel pressure and 23in of vacuum at idle. Maybe that's just the personality of this particular $300 engine lol
I've had issues with rough idle in the past and it was always ignition related. Remove your coil packs, lift up the module and clean the mounting surface with a wire brush and or emery cloth. Wipe residue with a clean cloth and electric contact cleaner (if you have it) Make sure that this surface sees a solid ground or run a separate ground wire there (3800s had a ground strap there). Put coil packs back on the plate ( don't use thermal grease) and tighten firmly but not excessively tight or you will break or strip out the 5.5mm screws. I did this and the idle is now perfect.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 07-28-2024).]
I always assumed that the 3800SC just idled rough while sitting because of being Supercharged. I have two F23/3800SC swaps. One I have had for 10 years that idles rough just as you explained, but when I drive it, it runs smoothly. My other one is in the process of being swapped. Crazy thing is I thought this same exact thing if my second swap would idle the same way. I guess I'll find out in a few weeks. With everyone saying a stock swap should not idle rough, I may have to investigate further on my first swap.
Sounds good. What is the idle speed there, and what has the exhaust system been made up of?
Umm I'm an idiot, and you know that lol.. umm what ever is stock, yes, I should know, my attention when I start it is on oil pressure... What ever stock OEM is, 750, 800? The exhaust is somewhat simple / convoluted. ZZP power logs front and rear, Home build 2.5" manifold to homebuild 3.5 inch long ' mini convertor' down into a homebuild muffler mimicking the 2.8 muffler ( think making everything internal bigger' ) OEM tail pipes
[This message has been edited by jelly2m8 (edited 07-28-2024).]
If your CAI used an oil lined filter, you might need to clean your MAF. The oil from the filter can get on the MAF element and skew the readings.
x2 found out the hard way. Those K & N permanent air filters last a long time but the oil in them WILL throw off the 3800 MAF readings. MAF cleaner corrects the problem there but with the stock Fiero engine all should be OK as it uses a speed density system without a MAF sensor.
x2 found out the hard way. Those K & N permanent air filters last a long time but the oil in them WILL throw off the 3800 MAF readings. MAF cleaner corrects the problem there but with the stock Fiero engine all should be OK as it uses a speed density system without a MAF sensor.
Yep, I went a bit too far on my last K&N, 10 years no oiled cause I don't want issues. one day I though hmmmm seems a lil low on power
tossed that, put a new one in, 7 inch long one this time, all the Wirrrrrrr noises back
Thanks. I thought maybe it was idling smoother because it might've been idling a bit faster.
quote
Originally posted by jelly2m8:
The exhaust is somewhat simple / convoluted. ZZP power logs front and rear, Home build 2.5" manifold to homebuild 3.5 inch long ' mini convertor' down into a homebuild muffler mimicking the 2.8 muffler ( think making everything internal bigger' ) OEM tail pipes
Sounds good while idling. Does it drone at any RPM while driving? I put an aftermarket exhaust system on my turbo Subie. I love the sound of it 90% of the time. The other 10% of the time, the drone gets kind of annoying.
I've owned 2 3800's, 1 N/A, the other S/C. The S/C I bought new and can't recall ever having any complaints about idle. The N/A motor is at 170K and still idles smooth. Have you looked over the vacuum lines/gaskets? Next I might look at the injectors. The rubber hose on the N/A we're worthless, took care of all the rubber and thats where I'm at.
Sounds good while idling. Does it drone at any RPM while driving? I put an aftermarket exhaust system on my turbo Subie. I love the sound of it 90% of the time. The other 10% of the time, the drone gets kind of annoying.
No, I do not notice any droning and none of my passengers I asked ( motor heads ) There is only so much you can do with an odd firing engine, I am content with mine My only current self complaint is an early locked up torque convertor which locks up at @60-70KPH and drops the revs into slightly above Idle RPM ( which HOLY F/K ,IF I'm not bein a douche bag...... the MPH! ) This is simply PCM tuning which I'll get around to, for now below 80 KPH I pull it back into 3rd
My exhaust system is certainty most likely not the best, but I did my best to make it acceptable and something I can happily live with taking my car to car shows. Btw, I do run full Emissions, EGR, EVAP, a convertor, downstream O2. 'Not because I am green', but because I do appreciate a car that doesn't gas you out.
[This message has been edited by jelly2m8 (edited 08-10-2024).]
My only current self complaint is an early locked up torque convertor which locks up at @60-70KPH and drops the revs into slightly above Idle RPM ( which HOLY F/K ,IF I'm not bein a douche bag...... the MPH! ) This is simply PCM tuning which I'll get around to, for now below 80 KPH I pull it back into 3rd
