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what would cause BOG in 3800SC by Lou6t4gto
Started on: 03-11-2014 04:33 PM
Replies: 32 (372 views)
Last post by: Lou6t4gto on 03-14-2014 09:54 PM
Lou6t4gto
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Report this Post03-11-2014 04:33 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Brand new rebuild installation, 1998 buick 3800SC. starts and idles Perfect, but pull the throttle Quickly,(NOT under load, just sitting in park,) and it bogs ! the only things Not Changed are the MAF and O2 sensors. Ideas? anyone run into this before ? Shows No CODES. Thanks
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Phil
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Report this Post03-11-2014 04:35 PM Click Here to See the Profile for PhilClick Here to Email PhilSend a Private Message to PhilEdit/Delete MessageReply w/QuoteDirect Link to This Post
If it's an auto tranny there is a rev limiter at about 3000
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phonedawgz
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Report this Post03-11-2014 06:59 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
A MAF covered with a film of dried oil from a reusable air filter, or just dirt, will cause exactly what you are describing. Take out the MAF and look to see if it looks different front to back vs back to front. There is MAF cleaner. Break the wires and of course the MAF is crap.

The oil covering insulates the wire causing it to react slowly to air flow changes.

Harbor Freight has a reasonably priced set of bits $9.97

http://www.harborfreight.co...57.html#.Ux-jwT9dUrc

Sorry for posting a video that includes a dick. The dick does know pretty much what he is talking about however.

[This message has been edited by phonedawgz (edited 03-11-2014).]

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MstangsBware
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Report this Post03-11-2014 08:32 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

Brand new rebuild installation, 1998 buick 3800SC. starts and idles Perfect, but pull the throttle Quickly,(NOT under load, just sitting in park,) and it bogs ! the only things Not Changed are the MAF and O2 sensors. Ideas? anyone run into this before ? Shows No CODES. Thanks


U still on stock fuel pump?
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Lou6t4gto
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Report this Post03-11-2014 10:29 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Still have the stock 2.8 pump in the tank, ( I have the correct one, but have not installed it yet), but should that make a difference" when it's just standing still" ? This engine acted the same way BEFORE I removed it from the Riviera (no Power), so I'm guessing the MAF, just didn't want to drop $100 if that's not it. In the Riviera , Before I pulled the engine, it gave a MAF code and misfire #5, Now it "Shows" No Codes. so I guess I'll just get one and hope that's it. So, it Can't be the O2 ? ( If I don't need one, I'd rather not buy one). Thanks
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Report this Post03-12-2014 07:07 AM Click Here to See the Profile for ToosheaClick Here to Email ToosheaSend a Private Message to ToosheaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I used to have a GTP. I never really revved the motor in park. but I can tell you I had really bad KNOCK RETARD which made the car bog at medium throttle. The sensor is really sensitive on some cars and picks up knocks outside such as a loose exhaust clamp, loose motor mounts things you just wouldn't expect to affect the sensor. Well, I didnt answer your question but when you figure it out and you will.. Let us know!

------------------
Tim and Lynn
1987 Fastback GT in restore mode..

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phonedawgz
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Report this Post03-12-2014 08:40 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Clean the MAF before replacing it.
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carbon
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Report this Post03-12-2014 09:29 AM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Sorry for posting a video that includes a dick. The dick does know pretty much what he is talking about however.



Worst kind of dick... LOL I think he's funny.
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phonedawgz
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Report this Post03-12-2014 09:43 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Which drug do you think he has been abusing?
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bomluuk
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Report this Post03-12-2014 11:06 AM Click Here to See the Profile for bomluukSend a Private Message to bomluukEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check/change spark plugs and plug wires.
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Gall757
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Report this Post03-12-2014 11:33 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Which drug do you think he has been abusing?


it isn't novacane.....
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Report this Post03-12-2014 11:57 AM Click Here to See the Profile for revinSend a Private Message to revinEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fuel pressure is too low. Install a higher flow rateed unit.( corvette FP )
Yes even at idle it runs fine, in drive there is more load on the pump/engine.
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Lou6t4gto
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Report this Post03-12-2014 12:47 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Plugs/wires ENGINE, Everything is NEW, except MAF and O2. And orig fuel pump. But it won't Rev "Properly " In Nuetral" Standing Still, not even once. Fuel pressure at about 40 (gauge Connected.)
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Lou6t4gto
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Report this Post03-12-2014 12:49 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

Lou6t4gto

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will check plugs, it's only got maybe 5 min actual "Running Time"
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bomluuk
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Report this Post03-12-2014 02:09 PM Click Here to See the Profile for bomluukSend a Private Message to bomluukEdit/Delete MessageReply w/QuoteDirect Link to This Post
The last set of plug wires I bought had 1 wire that was no good. Luckily I metered them before I installed them. After replacing the plugs and wires (just last night) I took it for a short drive and I actually got the tires to spin. I was having a stumbling issue as well. When I get off work today I'm gonna take it for a longer drive, but I think my issue is fixed. I too didn't have any codes that read misfire or anything like that when I was having my issue.

Edit:
This is a video in one of my threads that shows what issue I was having. Look/Sound familiar at all?
http://www.fiero.nl/forum/F...HTML/130791.html#p19

[This message has been edited by bomluuk (edited 03-12-2014).]

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2002z28ssconv
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Report this Post03-12-2014 07:52 PM Click Here to See the Profile for 2002z28ssconvClick Here to visit 2002z28ssconv's HomePageSend a Private Message to 2002z28ssconvEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:
...

Sorry for posting a video that includes a dick. The dick does know pretty much what he is talking about however.

...



This one's hilarious!



Clean the MAF Lou.
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86soon3.4
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Report this Post03-12-2014 07:58 PM Click Here to See the Profile for 86soon3.4Send a Private Message to 86soon3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
You need more fuel pressure than what the stock one will put out.

Install the higher pressure pump and be done with it.


Steve
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Lou6t4gto
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Report this Post03-12-2014 08:32 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I am going to install the new pump. But, "seems to me", If Fuel pressure was the problem, it wouldn't have been happening while it was still installed in the Riviera.
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olejoedad
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Report this Post03-12-2014 10:05 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Lou, check your PMs.
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revin
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Report this Post03-13-2014 06:40 AM Click Here to See the Profile for revinSend a Private Message to revinEdit/Delete MessageReply w/QuoteDirect Link to This Post
You had a fiero 2.8 fuel pump in your Rivera?
Do a search for fuel pumps for the 3800sc.Tthere are many opions on which one is the best to use. I have always used the EP3** kind.( forgot the #) vette pump- direct replacement
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Lou6t4gto
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Report this Post03-13-2014 08:44 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
"You had a fiero 2.8 fuel pump in your Rivera", WHERE did you get THAT ?? when the engine was still in the Riviera, it still had the Riviera fuel pump running it, but still had "No Power", so I would tend to believe that pressure may not be the problem. ( I Have a suitable high pressure pump to install) I ordered a new MAF.
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Report this Post03-13-2014 09:01 AM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
It will run 99% fine without the maf plugged in.
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Lou6t4gto
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Report this Post03-13-2014 09:21 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
if it can run Fine without the MAF, I heard it will not, why are so many saying that these symptoms are of a bad or dirty MAF ? I'm open to "OTHER" suggestions.
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phonedawgz
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Report this Post03-13-2014 12:23 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
In earlier EFI, GM used either a 'speed density' calculation to measure the air flowing into the engine, or a MAF to measure it. Neither are perfect. On the 3800 GM uses both, thus giving the PCM better measurements of actual air flow, and giving the full sized car owner a redundant system that works pretty good even if one sensor totally fails.

If a sensor however doesn't totally fail, but instead gives bad info to the PCM, the PCM will act on that bad information and produce bad outputs.

[This message has been edited by phonedawgz (edited 03-13-2014).]

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Report this Post03-13-2014 02:57 PM Click Here to See the Profile for bomluukSend a Private Message to bomluukEdit/Delete MessageReply w/QuoteDirect Link to This Post
My car runs fine now. I'm using stock fuel pump. Had a bad plug wire.
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Lou6t4gto
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Report this Post03-14-2014 01:28 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
" 'speed density' calculation to measure the air flowing into the engine, or a MAF to measure it. Neither are perfect. On the 3800 GM uses BOTH," so where is this "other" sensor ? Can IT be replaced ? New MAF will be here Monday. Thanks
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olejoedad
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Report this Post03-14-2014 01:38 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Speed density is calculated using throttle position and other factors. There is no speed density sensor.
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carbon
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Report this Post03-14-2014 03:00 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
The stock Fiero ECM is based on speed density. Speed density calculations rely primarily on the MAP, IAT sensors and RPM of the engine. It uses the TPS to calculate acceleration enrichment, if you unplug the TPS in on a SD ECM you will have horrible throttle response but it will keep a steady speed like a champ... heck even a MAF system will be sluggish with no TPS...

The stock Fiero ECM falls back to an 'limp home' mode if the MAP is disconnected or fails... that is purely throttle position and RPM, it has no concept of load at that point and so it is programmed to run fairly rich to be safe...

GM MAF based ECMs fall back to speed density if the MAF fails and probably even the same 'limp home' mode of the Fiero ECM if very bad things have happened.

[This message has been edited by carbon (edited 03-14-2014).]

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olejoedad
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Report this Post03-14-2014 03:48 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for a better explanation, carbon.

[This message has been edited by olejoedad (edited 03-14-2014).]

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darkhorizon
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Report this Post03-14-2014 04:03 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
maf fail = MAP and TPS used to generate volumentric efficency using speed density calculations.

map fail = no changes, all 3800 ecu's do not use the map sensor for fueling

maf and maf fail = alpha n / TPS sensor is compared to RPM readings to generate required fueling calculations.
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Lou6t4gto
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Report this Post03-14-2014 05:10 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Is it "possibly" the TPS ?
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phonedawgz
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Report this Post03-14-2014 08:05 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
TPS is not used much by the PCM.

It is used to determine if the throttle is closed and the PCM should be controlling the idle speed.

It is used when you move the throttle quickly so the PCM knows to add extra fuel.

Since you are not getting a TPS code, it must be working at least some. If your TPS has a bad spot on it that spot can be read by the ECM as a quick movement of the throttle.

Not much chance however of the TPS causing this the way I look at it. If you have a scanner, turn it on, read the TPS - key on engine off - and slowly push the throttle open. If the scanner shows anything but your smooth throttle opening then suspect a bad TPS.

SD uses MAP, RPM and IAT to determine air charge, not TPS. TPS is quite useless when trying to calculate how much air is in the intake manifold compared to the MAP.

[This message has been edited by phonedawgz (edited 03-14-2014).]

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Lou6t4gto
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Report this Post03-14-2014 09:54 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
ahh, good to know. I'll check to see if the tps is working "smoothly". didn't realize I could check it with the hand held scanner. Thanks
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