Quick question

Karma wrote:

There is no MAP sensor on the series one.

Are you sure? I'd be surprised, even my '84 Omega had a MAP sensor. It's the only way for the computer to measure engine vacuum, a critical measurement. My '94 Regal had one too (SI 3800 N/A).

I don't have the repair manuals around for the Regal or I'd go look it up, but I'm sure there would be a MAP sensor.

edit: there's a listing for one on RockAuto -
http://www.rockauto.com/catalog/x,carcode,1022016,parttype,11207

Does anyone know where there is under hood pic of the series one without the engine cover on it.
I've searched on here for MAP sensor and related things but cannot find it.
Mitchell ONDemand discusses it, but shows no pic's for the 95.
I thought I remember seeing a MAP sensor on the back side of the engine somewhere.
I agree with Deek the car has to have one for the PCM to know what manifold absolute pressure, barometric pressure and intake vacuum is to make certain calculations.
At least that's what I've thought all along. How else will it know. (Speed Density Only ?)

the fsm for the 95 has no mention of a map sensor. And I looked on my 95 and dont find one. there are some pics of my 95 with the hood up in the show room, under "here are some pics of my ride" https://rivperformance.editboard.com/showroom-f3/here-are-some-pics-of-my-ride-t5917.htm

hope this helps.

Well then the 95 must rely specifically on "Speed Density" calculations from the Mass Air Flow Sensor and TPS for proper calibration of fuel and timing along with accurate readings from the CKP and CPS.
I can't even find a vacuum hose diagram from Mitchell or any other source I have.
I can find diagrams for other year engines I think, but not the 95.

deekster_caddy wrote:

Karma wrote:

There is no MAP sensor on the series one.

Are you sure? I'd be surprised, even my '84 Omega had a MAP sensor. It's the only way for the computer to measure engine vacuum, a critical measurement. My '94 Regal had one too (SI 3800 N/A).

I don't have the repair manuals around for the Regal or I'd go look it up, but I'm sure there would be a MAP sensor.

edit: there's a listing for one on RockAuto -
http://www.rockauto.com/catalog/x,carcode,1022016,parttype,11207

I'm absolutely sure. I did a bunch of research on this when I was seeing a MAP failure reading on the scan-tool, found that its "normal" because there is no MAP sensor. Rock auto sometimes has parts listed incorrectly, thats one of them. The 95 series one l67 does not have one. Same with 95 l67 Bonneville too FYI. Its all done with speed density.

I wish I was wrong on this, would be one less quirk on the engine for tuning...

Karma wrote:

There is no MAP sensor on the series one.
and FYI, my engine runs vac of around -25 in-hg

This 25"Hg could be used as a baseline, possibly for your engine as well. If 25" of vacuum is where you should be at (at idle) then you are clearly dealing with a vacuum leak based on your readings.

Okay, I stand corrected. I'm shocked there is no MAP, but if that's the way it is, so be it. It must rely strictly on TPS and MAF readings.

I was trying to dig up some of my old research into it, but it was ages ago, and I spent hours looking. I did scare up this:

Quote :

"No matter how much the tables are changed, it still can't won't be able to be "bi-polar"...it needs to be able to operate the car BOTH in n/a AND in turbo mode. Chrysler PCMs could do it because they had MAP sensors...it sensed boost, it changed timing and tables. Series 1 GMs didn't use MAPs...instead they were programmed to use mainly the TPS, MAF, and knock sensor to determine the strategies needed, but this method changed with the S2...those actually used MAPs."

http://pontiacbonnevilleclub.com/forum/viewtopic.php?f=12&t=12959&p=137741&hilit=map+sensor+95+series+one#p137741

Thanks everyone...Yeah I didn't think there was a MAP...I'm sure through my physical digging through the car that something would have turned up.

Well, I report back with findings that will confuse and confound you all even more. I disconnected my vac/boost gauge and put the original vac line back on to make the engine stock and eliminate the gauge as a possible leak zone on its own, then ran the scanner all the way home from work today, and that included a stop to my cousin's garage. Started the car up, and it was a cold start (coolant temp a residual 98F) and the car ran maxed-out lean until about 2 miles down the road where it leveled out and the fuel trim returned to normal. For a while, anyway. A few miles later the trim was maxed out, even when costing in 3rd gear. That being said, a few miles later, the car was at normal fuel trim levels and was even slightly rich coasting in 3rd gear. It flipped-flopped this way all the way to the garage and back home. No situation was the same - same gear, speed, and throttle position were yielding different fuel trim levels constantly every time I checked.

Since I was so perplexed as to why this was happening, as it had never been so erratic before, I didn't take the time to scroll down in my vehicle diagnosis page to see what the MAF had to say during this. I'll need to look at that when I start the car next. This is so strange. I'm not even frustrated anymore, just intrigued as to what could really be causing the car to lean out so easily. I'm about 99% sure it's a vacuum leak too now but the question now is, where could it possibly be that me engine light and idle problem is SO intermittent? That's mainly what's making the least sense to me - the situation being so intermittent. My idle didn't fluctuate and my light didn't come on the entire drive home, but you saw what I found according to the scanner.

I really do appreciate all the thoughts and ideas so far, gang. I don't expect you to solve the problem (because I only think a pro and tools would at this point) but I do appreciate all the insight, very very much. I'll keep scanning and keep you posted.

One thing I'm most curious about is a cold engine reading 98*F..
Did i catch that correctly or did you make an error.

Sorry my mistake...I meant to say that the coolant temperature was still about 98* after sitting for 3 hours while I was at my short day of work. What I wrote about after that was one my way home. Thanks for having me clear that up, my fault!

Ok another update...consistently for the past week my vac gauge has been reading 18 HGin at operating temperature, in idle, in gear. The only time it ever goes anywhere NEAR 25 is when im coasting in TC lockup around 55-65 mph. It'll definitely be going to the shop to find the vacuum leak and the possible cause of this issue. Also, going back to what someone else said in an earlier post here, I'm not getting any knock retard while the car is max leaned out, surprisingly and much to my relief. Now, something else...

On my scanner, the Actron CP9145 AutoScanner, there's two 'engine groups' I can look at to view data. The first group shows all of the sensor data coming from the computer, and the second group deals with engine misfires and things like that. I don't know how similar this is to other scanners, but if anyone wnats to know what data is in each engine group I'd be glad to list them. At the top of each 'group' in the menu it says CODES PRESENT: (yes or no) . In the first engine group dealing with sensors and whatnot, it says no codes present. This came as a surprise to me considering the code I'm getting, Fuel Trim Lean. In the second group, it says there's a code present. My Fuel Trim Lean code to be exact. I cleared the code and it went away from that group as well. I just don't understand why the code would be associated with the second engine group as opposed to the first.

Anyone have any more thoughts on this? I really don't have a clue at this point. I'm just trying to gather as much information as I can when it eventually gets to my mechanic. Thanks guys!

Alright guys...resurrecting an olllllllld post here, but this is relevant. I know you don't all want to re-read this post, so I'll sum it up. I had an idle problem that was quickly followed by a Fuel Sensor Lean code when coasting or idling. Couldn't figure it out for the life of me because the O2 sensor was reading fine on the scanner, and a vacuum leak could not be found. Also, this problem was intermittent so it had a slightly higher level of difficulty to diagnose.

So today, I finally had time to replace the O2 sensor. Here is what I found:



That'll do it...it literally explains everything that had been happening. So now that this problem is over (a long test drive in the rain confirmed it, IMO), I'm going to relax and enjoy the car much more now and not have to worry about what may or may not happen in stop and go traffic.

So thanks for everyone's help since last year with this issue...much appreciated.

all i see is a wire that had possibly a piggyback item attached to it. what do u mean?

robotennis61 wrote:

all i see is a wire that had possibly a piggyback item attached to it. what do u mean?

see the stripped bit?

yeah. but that wont alter the function of the 02 sensor unless water is spitting all over it right?

...which was exactly the problem most of the time. Usually when it was really humid or raining, I'd have the most prominent issues. Not always, but that's when it was most common. So yeah - the wires must have been pulled pretty good at some point because it's not brittle or anything.

I think that sensor needed changed anyway....it's been 120,000 miles.

Personally, I think it looks like the upper white wire has broken insulation near the perimeter, where it could go to ground...

You're right Eldo...I just pulled the sensor out of the box i had it in (keeping it as a memento for my troubles) and it looks like the 'upper' wire you were tlaking about is a bit pulled too. Grounding would be a possibility. more evidence those wires were pulled on at some point.

Crazy how one small minor piece of damage could cause so much grief.

Cool... thanks for the confirmation.

Quote :

Crazy how one small minor piece of damage could cause so much grief.

With electronics, that almost always the case.