Who knows how much vacum my tpi motor is supposed to pull when a gauge is attached? the gauge says 14 lbs. and the needle should be steady.


I have to check for leaks. just bought the gauge.

 

I think in the range of 18-22(stock engine) working at the post office burned some of my brain cells so I have to re-learn some things

 

the gauge says 14 lbs. normal motor.

I haven't tried it yet.

 

yup, 18-22 pnds.

 

that sucks, find the leak!

 

Sorry to hear about the leak, maybe it's good news though, hopefully this will finally fix your idle problem. Good luck.

 

O.K. Guys-

Yesterday was a good day for diagnostics. Hooked up my new vacuum gauge and walla!!! Gauge tells me I have a leak at the manifold. So I check the upper manifold torx/allen bolts and they are all loose! I just put this crap together…how could it already be loose! Anyway, I tightened all to 25 lbs.

Now, the vacuum gauge is hovering around 15 lbs. And spikes once in awhile. The gauge says late timing or something like that. Anyway, I ran out of starter fluid to spray around for leaks, so I stopped that.

Tried to set minimum air, idle, timing. Once the car threw a 42,24 code which says my (est) is grounded or shorted open. I cleared the codes and they will not reset.

Besides the vacuum situation, These two things are happening also:
1. primary fan will not come on when it is supposed to. (I confirmed the fan motor/relays/fusable links are good.
2. The gauge for volts on the dash is hovering like at 9 volts. It always read near 13. My scanner shows 11.4 volts at battery. I have had the following checked and they check good: battery/altern/ign. Module.

I think maybe the volt gauge and primary fan might be on the same circuit. When you load on accessories, ie: ac/headlights/blinkers, the volts drop on the dash gauge to around 8 volts. But the headlights do not dim.

Timing light and scanner show timing advance with est hooked up, so I think that is o.k., but I could not get my probe light to come on when I probed the est connector on both sides while motor ran. Shouldn’t it have power in there?, but the car is advancing it’s timing.


I DROVE IT AROUND THE BLOCK!!!!! It did not backfire or have excessive valve train noise. (remember I put in a lt4 cam/1:6 rollers.)

So, let’s all become electricians and trouble shoot the fan/gauge.

Anyone have the wiring diagrams for the dual fan set up and the diagram for the volt gauge?

Also wiggled the plugs at the ecm and pulled wires there, tapped on ecm while motor ran…no change.Fuse is good at fuse block for fan circuit. I have 12 volt source key on behind fuse, just no 12 volt under the hood for fans. I think I have a short causing the dash gauge to read real low.

Keep in mind this is a garaged always low mile, non beater. 70k orig. miles.

Could in proper rocker adjustment cause the low vacuum?, but can the volt problem be associated with the vacuum problem?

 

Maybe this will help?

Dual Fan Installation and Wiring

Wiring diagram on TGO thread

 

Does the fan come on too late?Mine did that,it wouldn't come on till about 250-260*.I put a new fan realy in(old one worked,just not at the right time)and it started coming on and 225*.I still thought this was high so I got the jet fan switch and it stayed at 195-200* all day.My old 84 t/a went through alternators like there was no tomorrow.Never found out what that was about.I would buy a new alt,you took it in to have it tested right?Try testing output at the alt.11.** volts is too low,the battery with the car off should read in the 12 volt range.Your voltage regulator may be bad,spiking at times.

 

Did some research on tgo all morning:

I feel the low vacum cond. is not associated with the fan/charging problem. However, fan and charging system do inter-relate. I have printed gobs of info about testing from ecm to the fans as well as alternator tests. I did take in the alty and battery...both tested o.k. BUT, my gauge on the dash tells the story...9 volts running.

 

I feel a bit' dumb founded, but solved the charging problem as well as the fan problem



1 bad fuse.
1 cut alt. signal wire in the harness.

I must have zapped that fuse the last time I put the alty back on....had it off and on like 5 times during this situation.

Now, to trouble shoot the 15 lbs. of vacum.

 

Nice job, at least it was something simple and cheap to fix. Hope the vacuum problem turns out that way also, good luck, you are on a roll so far.

 

i read that if you hook up a vacuum gauge to your intake before the throttle body, and drive the car, if you pull any vacuum, your not getting enough air, if you have no vacuum, your getting sufficient air.

 

Did the test....all are at 210 pounds.


that's good. My plugs looked like crap. Maybe today I will get a new set in and try to fire er' up again.


Other than the above, data logging/swap out ecm. then I don't know what else to do.

 

My guess is still to do the ecm and prom chip once you replace the plugs and that still doesn't fix the problem.

 

UPDATE!!!

The rock actually moved and drove. Here are the sysmptoms:

cold start up....idle spike,sharp swings from 1000 rpm down to 500 rpm.

say what the f#$%^&, take it out anyway.

get her on the freeway...***** out!, car cooks man! get off the freeway and she has a lumpy idle, but exceptable. Temp gauge is reading normal at this point. I do not have a aftermarket fan switch and I have a 190 thermo.

Redo the test, start car up cold, she bucks around, drive it anyway and at goes away at oper temp?

Should I replace the cts?

I just replaced the intake temp sensor underneath the plem, but have not started her back up.

Any comments?

Still have swapping ecm as a suggestion. Eric? you reading this?

 

before you change your cts/ect check to see if its bad or not

the CTS is a negative temperature coefficient thermistor so as the temp increases the resistence and voltage should decrease

typical resistance value for a NTC thermistor:
100,000 ohms @ -40*C/F
100-200 ohms @ 100*C(212*F)

and of course you have a 5 volt reference

 

My scanner does show the cts is working, but I am running out of ideas other than the ecm having problems. the car runs real strong on the freeway. after warm up, a slight rpm variation.

 

if its not a sensor maybe you have a vacuum leak be it hose or runners

have you ever just let the car idle to see if it settle, also sounds like the car may have been down awhile usually when that happens the ECM has to re-learn everything and that could take up to 500 miles

when its at operating temps does it still search for idle

fuel pressure?

 

Still sounds like the ecm to me, my car had the cold idle problems but smoothed out once it was warm, same thing your car has. It's the ecm, and or prom chip too.

 

I'm gonna' side with Will on this one...Eric says he has an extra ecm. before I go changing the cts, I ask him about the extra one he has...atleast just for a test.


Me thinks the red body color may have to change since I like to drive it umm....... too fast most of the time.

 

lol, yes please change the color, we have enough red iroc's in this group already. Let me know if I was right about the ecm, good luck.