Ok so I'm finally driving my car again after a year long rebuild....it feels damn good!! All the essential information is in my signature. I am having a few minor problems though.
The engine has a dead spot in it between 1500 and 2000 RPM's when cruising. I'll be going along and all of a sudden it will feel like I took my foot off the gas eventhough I didn't. Also the idle is very choppy and it stalled on me at a stoplight this morning.
The last key to this puzzle is a Code 13 that I got on the highway this morning. The SES light came on for about 30 seconds and that's the code I pulled. According to my literature that means "Oxygen Sensor- signal stays low(lean) during warm engine cruise".
Is there any chance that maybe a bad TPS or IAC or something is causing all of these problems together??

Another quick problem is that my brake pedal is very soft. It almost has to go to the floor to stop the car. I've bled the brakes 3 times normally and 1 time with the engine running. The master cylinder and brake hoses are new....also I just rebuilt the calipers.

 

What kind of cam do you have in there? If it has too much advance you will need a vacuum canister in order for the power brakes to function properly. I doubt the IAC is causing any of your problems. I would guess either the TPS, or maybe your timing is off. Oh, and did you reprogram your chip with the new motor? Hope this helps.

 

The cam is not too wild at all. Here are the specs:
Intake Exhaust
Gross Lift .5 .51
Duration (.006) 266 276
Duration (.050) 210 220

Lobe Seperation 114

Timing should be dead on around 12 degrees. I set it real good after I had the glowing header problem.

The chip was burnt by Ed Wright at Fastchips so it should be good, maybe it needs a little tweaking?
I got all my sensors from GM except the TPS which I got at Pep Boys.....is it possible this could be causing all my engine problems, including the lean O2 value??

 

Lots of reasons you could be leaning out. Do you have a scanner? Just because you had a chip professionally burnt doesn't mean it's right. Lots of info on DIY on the DIY prom burning board.

 

As far as the brakes go ...
You probably need to bleed the master...

If you have a large syringe or some such...
Tilt the car until the master cylinder is level or
abit "nose" down

While injecting fluid into the forward port
slightly loosen the line and then retighten before
you run out of fluid.

 

i'd consider learning to burn my own chips, that may fix your problems. you might want to look for a vacumn leak too.

 

I had wanted to learn how to burn my own chips, but I didn't think my brand new engine would be a good test. I'm probably gonna send the chip back to be recalibrated. What kinds of readings can I send along with it to help?? O2 readings??

Also I am going to use some carb cleaner tomorrow to check for vac leaks. I put a gauge on it a few weeks ago and it was pulling between 15-18 lbs at idle.

As far as the brakes, the master is new and I bled it when I installed it. Someone suggested tapping on the proportioning valve with a ball peen because sometimes bubbles can cause one of the valves to stick open/closed in it??

Also I am having a problem with heat soak on my starter now that I never had before. It's the same starter as always. The temp gauge on the car never really passes like 160-180. What's up with that??

 

Hmmm
It would be reasonably good if you could get to a dyno
with a wideband o2...

A plot of torque vs RPM
A plot of o2 vs rpm

Hmmm...
Bubbles...
Anyway how are you performing the bleed..
Not being a jerk about this but until I got my power injector
I had a fair amount of trouble doing this with other
than one or two folks. Never could get past the ...
"Should I pump it?" "Oh I thought you meant a lot"
"What do you mean hold it" kind of crap with
most available helpers.

 

Me thinks you're talking with the wrong person...unless things have changed over the years, there are no "valves" within the valve itself. The block is drilled/machined with openings to allow for flow. It's a valve itself, not valves within.

 

Yeah I didn't think there were any actuating valves in the proportioning valve. I'm probably gonna get some brake hose clamps to help me isolate the problem. They are working enough for now to drive.


I'm more concerned with solving these engine gremlins. I drove it again today and again it stalled at a light and I had to push it to the side of the road and let the starter cool for 25 minutes!! Needless to say I was a little late to work.
Does the computer chip have a specified value for idle speed in OD/D?? Would this override any manual idle adjustments?
I'm going to test for vac leaks tomorrow, but I'm hoping that's not my problem.

 

Code 13 means the computer isn't getting any input from the oxygen sensor (code 44 is the one you guys are thinking about). Is your oxygen sensor plugged in?

 

If you have rear drum brakes, there is a residual pressure check valve incorporated into the proportioning valve body. Still, if air bubbles are sticking the valve, you have more problems than just air.

As for the cam, I know it well. You should get respectable vacuum with it.

And excuse me if I missed it along the way, but are you still running a MAF?

 

I am still running my MAF setup and as far as my charts read the code 13 is for a lean O2 sensor reading.
If it stops raining I'm going to test for vac leaks with some carb cleaner and post my results.
However I still think chip or sensor because I have a terrible loss in power between 1500 and 2000 almost all the time, and at no other RPM range.
Also can someone answer my question about the computer controlled idle speed in gear.....I turned the idle up a little today and it didn't stall, but it still felt like it was going to.

 

Paul, do you have access to a scanner? The TPS and CTS are really easy to check for proper operation with a scanner. The TPS voltage should move smoothly up the scale ffrom what ever you have it initially set at, say .54volts to 4.5 (I think). While driving, watch the TPS voltage. Slowly accelerate and see if the voltage climb is linear. It should not be jumping around.
Same with the CTS. Watch the temp as the car warms up. It should naturally climb and somewhat match the gage in the car.
Using my recent O2 problems as a reference I'd concentrate there. My car would do what yours did, on fast deceleration the idle would hunt around, almost stalling. You could see the IAC trying to compensate but never quite keeping up. The pintle can only move so fast. Also the injector PW would climb through the roof, dumping fuel to keep the motor running. Check for O2 leaks around your header collector gaskets, header gaskets and the AIR tubes if you still have them. That was my initial problem.

 

How should I check for leaks there??? Soapy water???

I checked again for a vac leak tonight. I sprayed carb cleaner all around the intake duct work by the MAF, all around the injectors, the fuel pressure regulator, the runners, and the throttle body. No engine racing at all which actually makes me happy. I guess that leaves me with something electrical or possibly fuel related right??

 

good chance you have a bad tps and you need to replace your o2 sensor. take a digital volt ohm meter and conect it to the pins in the conector on the tps on slowly depress the pedal, watch the meter for glitches. that will be your dead spot. these happen because the potentiomoter sits at that same spot when crusing and wears that spot away.
thanks
anthony

 

ok well I'll have to wait until friday night to throw a meter on it because the car is going back to the paint shop tomorrow for the painter to put my door decals in the right place and buff out my new rear decklid.


Explain to me in detail how to check/adjust the TPS because I was confused as anything the first time I did it. What I ended up doing was placing jumpers between the TPS and harness connection and measuring the voltage across the jumpers.

Also would a bad TPS cause that lean O2 reading? I don't see how both my new TPS and O2 sensor would be bad?

 

I don't know how a bad TPS could cause a lean O2 sensor reading. It would more likely give you an erratic idle etc as the computer would think the car was accelerating/decelerating when it was not. Perhaps it could casue a momentary lean condition.
Base voltage is .54 from the factory. I think WOT should be 4.5 but check the tech article.

 

Let me preface my guess (and everyone's guessing so far) by saying that I'm NOT saying this is necessarily your problem. Just some info to stick in the old bio-computer as reference material.

My brother's 87 had the EXACT same symptoms as yours. Went through all the vacuum leaks, TPS adjusting, bad ECM, bad module, wrong fuel pressure kinda stuff. Still had an off-idle flat spot, would throw a RARE lean O2 code, and was also a bit rough idling, especially when cold, occasionally stalling.

End of the day, the ECM, for once, was actually pointing us in the right direction. LEAN LEAN LEAN. Brother finally admitted that he bought his "30# SVO injectors" off e-bay from a private party. Ran the numbers- SORRY, CHARLIE- 24#, not 30#!. In went a set of properly sized Accel injectors and suddenly no more problems. Ran PERFECT. Having the injectors not matched with the injector constant programmed into your chip drives MAF-type systems COMPLETELY BONKERS.

My expereince with the Code 13 is that it takes a LOT of running lean and under conditions that are just perfect to throw that code. If you're got a Code 13, it probably IS running lean. Our block learns (Diacom verified) were ALL maxed out at 160 (high as it goes to richen the mix) due to the injector mismatch. And it STILL would only throw a lean code maybe once a week or so.

 

Well I won't have the car back until tomorrow night so I can't do any other tests today. I will check the swing of the TPS voltage and I'm going to throw my old 305 chip back into it and go for a ride. I know the whole car will be down on power, but I should be able to feel if the dead spot goes away. This should tell me if it's the chip or not right?

Also the code 13 only turned the light on for maybe a half minute and hasn't come back on yet. Couldn't a bad TPS or incorrect fuel/spark curve cause this to happen??

 

if you test the tps clip the conectors of the meter to the terminals on the tps. it is as easy as that. if there is a dead spot, buy a new one.

and no a bad tps would not cause a lean o2 sensor. that is an altogether diff. problem.

had you had taken your car to me to fix at work, what i explaned would have cost you about 100 just to test the stuff and change it. so be happy, im trying to save you money. it could be worse.

thanks
anthony

 

Hey, KKer,

Is that the new style "stealth" mirror?

 

also paul i would make sure that when u get parst from the bridgewater pep-boys, that u make sure that part is what u need. becuz i work at pepboys and since being transfured to the new pep-boys in watchung the bridgewater store has gone down hill. just alittle advice on if ur goin there serchin for parts and if u do go to bridgewater pepboys, see if Derek ( not sure on spellin) is workin that day becuz he can make sure u get the right part and if he doesnt then he's slippin over there. later

tim

 

somthin like that, its in the car. like my ram air

 

damnit that post by momar is by me. hears my disc brake cooler.

 

Thanks for the tip on Pep Boys but I usually just lean over the counter and look the parts up in the computer myself.
Maybe tomorrow I will have a chance to check out the TPS. One more quick question though on testing it. Do I need to create a set of jumpers between the TPS and harness so that there is a reference voltage or not??

 

no mesure using the ohms setting on the meter

thanks
anthony

 

OK well I installed a new TPS and still had the same problems. I also reinstalled the factory 305 chip to see if the dead spot would go away and it didn't.
I was talking to the service manager at Pep Boys, not that he's exactly the best person to ask, but he said it's probably the pick-up coil if it's only cutting out at a certain RPM range. He said if the module was bad then it would do it at all speeds.

Any quick thoughts before I pull the distributer??

 

it could be the coil, but when a tps sensor has a worn spot, that creates a dead spot but will not totaly kill the engine, thats because even though the swing arm of the potentiomoter (sp) does not make contact, the coiled wire that the swing arm slides against is still intact, just worn in one spot. hope this makes sense, its kind of late at night.

anthony

 

On the brakes did you hook up the vacume line to the booster?
I forgot that when I put in my engine and the brakes were really soft.

 

Yes the booster hose is connected. I have another post going for my engine problems so please see that for further information.