Section_25

Hi Folks,

First post here, but used this forum for months for help here and there on my camo that I have been trying to restore. I will TRY to keep this short and sweet, but no promises

91 Camaro RS (305 - 5.0) automatic with a rebuilt motor approx. 3 years old, after several months sitting in my driveway, I'm finally getting around to putting some time and money into this car. Paint was really getting bad, so I took it to maaco and let them paint it (was shocked at the excellent job they did IMO), then did the routine maintenance (oil change, trans checked etc...). The car runs fine as is, however I do have a couple of questions I was hoping someone could answer and possibly point me in the right direction.

First question is about the tachometer, yes the infamous inaccurate tachometer issue. I saw a couple of threads here regarding this issue, but I wanted to ask again anyway. When the car is warm and I start it, all the gauges on the instrument panel read fine, but the tach reads around 1600 rpms, but I dont think it's actually running that high. I took the car to my brother-in-laws house (he is better mechanic than I am), and he said that it was not reading right. He attempted to connect a meter and see if the tach was accuarate or not. He swears it was connected in the right place, but he was unable to get any reading at all. The next day I found an identical tach at a salvage yard on a really decent looking camaro, so I bought it. Installed this other tach, all the gauges worked fine except......yes.....the tachometer, which reads slightly higher then the tach I had in there originally. I am assuming that the problem lies somewhere outside of the instrument panel, but I'm not sure where to look or what to try to fix next to resolve this issue. Whew.... ok, second issue

Second issue is the SES light..hehe...fun fun.... SES light comes on after I get out on the highway and drive for approx. 20 min at around 70-80 mph, then when I turn off the engine it resets, and does not come on again till I'm on the highway again at around 70 mph for 20 min. It does this almost everytime. I took the car over to my B-I-L house again, and we connected a code reader to it, and it comes up with code 32 (which I think is related to Fault in barometric pressure sensor circuit OR Fault in exhaust gas recirculation valve diagnostic switch OR Fault in electronic vacuum regulator valve) I did replace the egr valve, but I still have this same issue. Talked to another mecanic I know that advised me that it could be a vacuum leak. I haven't started to replace any vacuum hoses yet, but I wanted to ask in here and see if I could get some feedback and opinions on this. Any advice or opinions are welcome and appreciated

Section_25

Wow!

Must be some tough questions, over a week and not one reply

hot92RS

Rule: Start with the easy and least expensive probable solutions first. Take the vacuum issue, those lines are very inexpensive and easy to replace. Do you have a manual for the car? This will help you to diagnose those problems w/o calling your b-i-l, tentatively diagnose yourself, then call him to confirm, you'll learn a lot more. W/O looking I couldn't tell you about what to do w/ a code 32, but this site has been really helpful to me in my restoration and maintanence of my camos. Right now, I am doing a headliner repair and recovering because of a post by one of the guys on how to do it. Been to other camo sites and this one is the best.

Section_25

Well, changing the TPS and the vacuum lines must have fixed or helped the situation. Haven't seen the SES light in awhile. Car runs really rich though. My buddy swears that it is normal, but it just seems kind of extreme to me. Start the car and you can smell the exhaust from 20 feet away. Was thinking about changing out the O2 sensors, but it seems like a real PITA to do. Looked in the chilton manual and it basicly says to use extreme caution removing the one on the manifold. Not sure how many there are either, some ppl say 1, some say 2, and some even say 3.

tony_cogliandro

iTrader: (3)

my 91 always ran rich on the startup but seemed to get back to normal after it warmed up. and when it first started it always ran higher on the rps until it got hot. you could watch it and then as it warmed you could watch the tac go down to about 650.
or is yours running high all the time?

Billy_Bob

In modern vehicles, everything runs by electrical sensors which input information into the engine computer.

Then based on the information provided to the computer, it will adjust timing, fuel/air mixture, and idle speed to the right settings so everything runs as good as you can get.

BUT a sensor which inputs information to the computer can be faulty and might input the wrong information. The computer then adjusts the engine wrong. But what can it do? It can only base its decisions on the information it is provided with!

For example the engine computer adjusts timing based on information from electrical sensors which monitor the following things...

Crankshaft position
Engine speed (RPM)
Engine load (manifold pressure or vacuum)
Atmospheric (barometric) pressure
Engine coolant temperature

So how do you know if the various sensors are working properly or not?

Testing is the answer to that!

And instructions for testing all the various sensors in a vehicle can be quite long and detailed. Thus you need a BIG book!

And there is such a book, or rather set of books which explains in detail how to troubleshoot all these things. That is a *Factory* service manual set which is written by the manufacturer of the vehicle and used by professional mechanics.

These books have basic service instructions, replacement instructions, wiring diagrams, explain how each little sensor or gizmo on the vehicle works, shows locations of everything, gives pin numbers and wire colors of electrical connectors (then you can test a specific wire in a circuit), and on and on.

I have a 92 factory service manual set which has a basic service manual about 2 inches thick, an 11 x 17 large book 3/4 inch thick of electrical diagrams, a 3/4 inch thick fuel and emissions book which has all the engine computer stuff in it including diagnostic codes and how to troubleshoot these, and a unit replair manual 1 inch thick which says how to tear down and service things like the engine, alternator, axle, etc.

So I look at these factory books as a basic tool these days for servicing vehicles. I don't see how anyone could properly troubleshoot a modern vehicle without this information.

These factory service manuals can be ordered from your dealer or here...
http://www.helminc.com

Also there are online services like Alldata which provide the same basic information, but you have to pay a regular fee. But this and "CD" versions of repair manuals have the advantage that you can search to find something.

I prefer the books because I can take them out to my vehicle while working on it. Also I can look through the books and see what all is in them. Sometimes I don't know the right word to look for, but can find the section by flipping through pages. Like a Check Engine Light can be called that or CEL, or CES, or SES, or MIL, or Engine MIL Light (would under E in index!).

BTW I have been in the electronic service business for most of my life (non-automotive) and we always use factory service manuals and documentation for repairs. Just about anything which can be repaired has a factory service manual available from the manufacturer. Like refrigerators, furnaces, air conditioners, small engines, chainsaws, etc.

A quick read of the pertinent section in these manuals and you go from "I don't know what the problems is???" to -> "I see how that works, maybe this or that is the problem!"

hot92RS

Good advice. I emailed the link you provided. It seems to think that if I put my name and zip that I am some kind of dealer. What's up w/ that?