ZZ4TPI, Edelbrock hi-flow intake, #24 LT injectors, AdjFPR, headers.
All of a sudden, the car started running really rich. I have no a.i.r. pump/lines or egr but do have a cat. Exhaust is so rich it makes your eyes water!
I got my Chiltons out and it said if I grounded the ALDL A+B while the car is running I'll be in the field service mode.
Open loop causes the warning lamp to flash 2.5 times a second. CLosed loop once per second. Car seems to be in Open loop all the time, i.e. temp comes up to 180-200 where I have the fan temp switch set and the light still flashes 2.5 times a second.
I pulled my adjFPR tonight and inspected it. She seems to be working fine. Could this be a O2 sensor thing? Funny thing is no codes are getting set in the computer.
This all started earlier this week when the car started running like crap. All plugs were pretty black, 2-4-6-8 seemed worse then 1-3-5-7.
No I don't have a scanner but wish I did. COuld it have anything to do with CTS sending a wrong signal?
Could the AdjFPR be screwing up somehow? I have a fuel pressure gage and backed the pressure way off and it still seems to run rich.
I need some help fast, I'm heading out of town for a month and the wife needs her car running properly before I leave.
Thanks!

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Whats the matter? Topic too tough for all the experts? Bet if I asked if TPIS or SLP was any good I'd have 500 answers by now.
Thanks!

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

They'll probably say "24# injectors without a corresponding eprom = rich condition".

Sorry, but with the limited information that is the best I can say. In closed loop, the ecm SHOULD be adjusting the BLM/INT to derive 14.7 if your O2 sensor is functioning propersly and your CTS is also. What temperature range is your T-stat?

There are a variety of possible reasons for this, but without a scan tool (checking for Trouble codes may not work), you will only be getting "guesses".

 

Glenn,
the thing with the #24 injectors is I have had them in the car over a year with no problem. S&P Chip designed for ZZ4TPI.
I had the injectors cleaned and flow matched by Rick at Cruzin Performance before I installed them.
The T-state is a 180deg and I have an aftermarket fan switch. Car runs steady at 180 deg on the dash gage. A tinny bit colder on a scanner as I remember from the last time I had access to a scanner. This past January I took the car on a 1275 mile road trip with no problems. Pulled 21-22mpg at about an 80+mph plus average speed.
The fuel pressure still seems erratic at times looking at the gage.

A GM Tech told me system will stay in open loop cause the O2 senses a too rich condition. He said to draw a vacuum on the regulator, if I get gas its bad, or unplug the ecm and then check voltage in the injector harness, looking for a dim bulb indicating a frayed/shorted wire which would
cause the injector to basically spray continiously.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Thanks for the information Rob, it is helpful.

If your O2 sensor was completely "toasted" you would be getting a code 45 and the SES light would come on, especially on a "load" condition like part-throttle up a steep hill.

Now, a "weak" O2 sensor will not necessarily trigger a SES code, but it won't work properly either. I have seen this a few times. Very common with guys with headers where they don't have a heated O2 sensor...the O2 sensor works enough to not trigger a SES code, but not enough to funciton properly.

Now if it was other sensor, (MAP on SD, or MAF) they too will trigger a code. But a stuck or "weak" T-stat or a weak CTS won't necessarily and they may be the root of your problem as you surmised.

If you temperature guage is functionally normally and you get plenty of heat from the heater (you should with a 180* T-stat), then you can assume the T-stat is fine...that leads us to the CTS.

If the CTS is "weak" and does not trigger the minimum temperature requirement in your eprom (stock is around 115*F), then your car will not go into closed loop and you will rely solely on the tables (which tend to be on the rich side). Further, the CTS is very important in calculating the injector pulse width. When it is senses "cold", you remain in "cold start" procedure which further "richens" you on top of your tables and possibly extra fuel pressure.

You mentioned that your plugs are "black", a good indicator that you are running rich. Another good sign is if your fuel economy has recently deteriorated. If it has, then I would say the 3 culprits are your O2, T-stat or CTS. If you have an automatic, you will also notice that you cannot "lock" the tranny in O/D, as it will not do this until the engine has met the minimum temperature to go into closed loop.

The easiest way to test the CTS is with a scan tool. But if you have a multi-meter, you could measure the resistance across the CTS. At 180*F, you should be getting a resistance of around 330 ohms. A reading over 1,000-1,200 ohms would signify less than 110-120*F and that is roughly the temperature you need to go into closed loop.

If you are somewhere in the middle, then either you T-stat is weak or your CTS is weak. You most definitely should be reading around 330 ohms if you have a 180* T-stat.

One other caution, if the T-stat is weak and the CTS is good, you MAY get readings below 330 ohms because your engine would get hot while sitting their and idling. But if it NEVER gets below 1,000 ohms, that would indicate a weak CTS as your T-stat becomes irrelevant.

But hopefully, this will help you "zero in" on your problem without needing a scan tool.

(They sure do make life easy though).

 

Glenn,
Tks again for the help. I did stupidly cut the wire to the o2 sensor to lengthen it when I installed the headers, but it was like that for the 1275 mile trip. Maybe it degraded.
I probably will install a new CTS, they're pretty cheap, and that will eliminate that. First I'll check the readings, I do have a multimeter.
Looks like I'm busy this weekend!

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Rob,

I just saw your post. Do you have a scanner? I'd like to seem some diagnostic info ... Does the computer report open or closed loop? What are the BLMs and INTs at idle after the car has been running for 5 minutes? How many O2 crosscounts? Have you verified the timing? What is reported for BTDC timing on the scanner? What is your MAP at idle? How do these variables change when you are at constant speed on the highway?

Tim

------------------

• Program your own PROMs!. Read my article to get started!
• Research and Experiment before asking questions.
• This is not a chip store. Go to the classifieds if you want someone to sell you a chip or give you a BIN.

TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I agree with Traxion about the value of a scan tool in a situation like this, it would definitely answer a lot of questions. If the CTS seems fine and the wire is properly connected together (especially if it is a heated O2), you can rent a scan tool (Diacom) from TPIS for $50.00/week.

I would hate to see you buy a new CTS, a heated O2 and STILL have the problem. It was one of the principal reasons I got Diacom because I have seen friends chase a sensor problem, buying sensor after sensor after sensor; and still not fixing the problem. I figure my scan tool has already paid for itself just in tracking down problems; and then having it for eprom burning was a complete bonus.

 

I was looking into getting the cable and software for my laptop computer. Just not a good time for a scanner or a laptop pieces financially. I very well could be in need of a heated O2 after my recent SLP 1 5/8 header install. Are the temps inside the headers that much different from inside the exhaust manifolds? Thanks for jumping in Trax, of course I can't get the answers without a scanner, no one I know here in Jax seems to have one to borrow either. Of course like I said, I'm pressed for time, getting underway Monday (US Navy) for a month and it's the wifes car!
Question: Where do I hook the third wire of a 3 wire heated O2 sensor too? I would guess a Hot on Run lead? Thanks
Oh, this is an SD set up, forgot that.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

[This message has been edited by Rob P (edited February 01, 2001).]

 

Rob,

For the heated O2 sensor most guys use the switched 12V from the Fuel Pump relay. No matter what ... use a switched 12V

Good Luck!
Tim

------------------

• Program your own PROMs!. Read my article to get started!
• Research and Experiment before asking questions.
• This is not a chip store. Go to the classifieds if you want someone to sell you a chip or give you a BIN.

TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

TRAXION, Glenn
What if everything checks out fine. What's next?
BTW, I do have a scanner from SUNPRO and everything is fine. Changed all those parts not long ago, but didn't help.

------------------
'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, intake pieces and 2100 RPM TQ

13.40@102.55 MPH
1.90 Sec ------- Best 60FT
104.23 MPH -- Best Trap Speed

AIM HIGH!