Drewmeyes88

Ok so I bought a 88 firebird not to log ago. I replaced the plugs, rotor and cap and the coil. It still has a slight miss at like 1500-2000 rpms and I think that might be my distributor because it was rusty and green inside it. So thts on the way. But it also is worse when the engine is cold but then will return to how it usually is. The exhaust smells like a lot of gas I mean it's stronger then most cars I have drove. I cleaned the mass air flow with maf cleaner and it seemed to help a little. We did a fuel pressure test and it was at 44psi or 45. And the idle is a little jumpy sometimes like 500-700 it will go back and forth. If I floor it the car will go it will burn out and run good but if you barely hit the gas it kinda surges I guess? I think it's the miss. But thanks guys hope we can figure it out. Oh and I forgot I bought the car from a friend and he took the thermostat out cuz it was overheating but his radiator was plugged sp now I have a 2 core all aluminum. And it runs at like 120-160 I'm guessing

NathanLewis

spray carb cleaner into the intake.

92RSTPI

Likely a couple issues here. The dist cap would explain the missing/surging, but would likely not get better as the car warms up. It sounds like this needs replacing anyways, so I'd start here.

The MAF could be the issue, since you are stating it runs rich and runs better at WOT.

Drewmeyes88

Ok well I'm Waiting on the distributor it should be here Monday. But what do u think about the thermostat. Do I need to put one in? And I was hoping it wasn't the maf because they are like 150 haha but oh well I'll see what the distributor does and go from there. Thanks guys

Coolnyjay

The computer in your car would like the temperature to be around 220 degrees and will behave like a little B until it gets what it wants! Hence running rich. If you know how to program a chip then go for it. If not then I would say put in a 160 degree stat and get a hypertech thermomaster chip. Unless you have lots of mods then you will need a custom chip.

ex-x-fire

Just put a stock t-stat in it, forget that 160* crap.
Put the fuel pressure gauge back on it, does the pressure hold after the engine is off? This is important, because it helps to determine if you have a leaky injector or regulator.
Might have to have it scanned for smooth tps operation.

Drewmeyes88

Ok so I will check the fuel pressure shown but I'm pretty sure it held pressure after I turned it off. I have no service engine light on so could it still be my maf or o2 or any sensors? What about a fuel filter I haven't replaced that since I bought the car I mean it's pretty rusty and looks like it's never been replaced. Could the thermostat be causing any of the problems? Thanks

Also I installed the new distributor and wires and timed it at 6 degrees advanced and it still has the same problem.

Drewmeyes88

I got my codes ran it said tps low and maf low? I read on here and replaced my relays and I replaced my tps I still have the same problem? What do I do? I don't even have any codes on. Could this be a fuel filter or no? How do I test the maf?

fireburdluvr85

unplug the maf and start it. does it run better? that's a good test to see if the maf is causing the issues. do you have access to a data scanner? that's the best way to see what the engine sees. i wanted to add something from up above here, i have the stock 195* thermostat in mine and it never runs 220* runs around 190* and runs pretty good. just wanted to add that. i do have the 204* fan switch but it only kicks on during traffic.
also tps low? you need to see where it is cause it may be set improperly. it needs to be at .54v at idle. well that's spot on. my modis tells me that it can be +/- .06 in either direction. i like spot on tho. any setting lower then .48v will set a tps low code. at least in my experience it has. those two codes tend to go hand in hand. if your tps isnt set right it wont idle worth a damn on the computer side of things so it wont "read" the proper amount of air as fitting into any particular cell. set the tps. then go for a drive, see how it runs then report back to us.

Drewmeyes88

Thanks for the reply I will unplug the maf after work today. How to I check how many volte are at the tps? With a voltmeter I'm guessing but what connector do u put it in??

Drewmeyes88

Ok and I did do a fuel pressure test again the other what psi should it be at when idling? And how fast is it supposed to bleed down?

skibum2100

Check the TPS volts at the connector, un-clip the cover (leaving the connector in place on the TPS), measure the volts between the top two wires (A and B, think), it should be 0.54v

Fuel pressure should be 42-47 psi with vacuum line removed, so your 44 is good. The pressure should hold for ~45 seconds after the engine is turned off. I had 4 leaky injectors and the pressure bled off completely (to 0psi) in 2 mins, and it ran pig rich all the time.

Check on your fuel pressure regulator diaphragm as well, by removing the vacuum hose and smelling for fuel inside the vacuum hose.

Check for leaky injectors by opening the throttle body blades and smelling for fuel inside the plenum.

Hope this helps.

Drewmeyes88

Ok thank you I will check the voltage. Does it matter any way I put the tps on the tb? And my car was at like 25 psi like 10 mins later after I turned the car off. It is just getting so confusing I am running out of ideas.

skibum2100

Yea...it can be pretty daunting, but don't loose hope.

I believe you have to install the sensor with the connector pointed toward the front of the car and on the passenger side of the TB.

Check the CTS cold and hot to make sure its values are different. If the CTS sends a false cold signal it will over-richen the mixture. It is on the front of the intake manifold and towards the driver side.

Please change the fuel filter, it is cheap insurance.

Do you have access to a scanner, either home-made or professional? This info could be very helpful.

Hope this helps.

Drewmeyes88

Ok well I will check the cts. Well I had the codes ran today. Now I have a code 22 I think it said tps low, code 33 maf high and a code 36 maf burn off fault. I replaced both relays and the tps? I don't get it. I am changing the fuel filter tomorrow. So how do u Make a home made scanner?

skibum2100

I was able to build an ALDL cable to connect my car to my laptop, voila scanner. Check out this website, specifically How to build a cable. I would never have solved my surging idle without a scanner.

http://winaldl.joby.se/

Good luck.

Drewmeyes88

ok well i willl order one of those cables tomorrow. is it a pretty good program they let you download?? oh and by the way I put a new fuel filter on and nothing changed...thought id try though.

skibum2100

I love the program they let you download for free. There are better scanning programs for sale out there, but I haven't found any free ones that are better. Anyone else feel free to chime in here.

If you can use a soldering iron, then you too can build an ALDL instead of ordering one. It only took me two trips to Radio Shack and one afternoon.

Have you gotten the TPS mounted and adjusted yet?

I am still concerned your injectors may be leaking. Please put the pressure gauge back on and monitor how quickly the pressure drops. Don't forget about the Cold Start Injector, it may be leaking as well.

You can test to see if the injectors are leaking by:
removing plenum and one (driverside preferred) runner,
remove fuel rail bolts (keep the fuel lines connected),
lift the fuel rail (including the injectors) up just enough to get some clean papertowels under the injectors,
pressurize the fuel rail,
look for fuel soaking into the paper towels.

You can test the CSI for leaks as well; by rotating the CSI and tube upwards, pivoting at the fuel rail, you can get a paper towel under it too.

I chose to upgrade my original 1-wire o2 sensor to a 3- or 4-wire heated oxygen sensor. I prefer the 4-wire because it has a dedicated ground, instead of relying on the ground through the manifold and into the block.

Hope this helps.

Drewmeyes88

Well I just did a fuel pressure test the other day and it held pressure for a while. Me and my friend left it hooked up while we were working on his car and i came back and it was at like 25psi still.

I'm not the best with electronics and I haven't ever soldered so I think I may just buy it haha. Unless u can give me some tips. Do u think I should just take it to a diagnostic shop or am I going to get just as good results with this program. Will I be able to get like real time diagnostics with this? Can I drive with it hooked up? Could I ever get a program to tune with it?

And today I got my tps figured out we set it at .54 volts that is right isn't it? And I hooked a vacuum gauge up to my car and the spot it missed it was saying the timing was off and it wasn't advancing?! That's weird right? I am just lost on this one. I don't know what else to do. I even hooked up a new maf sensor today and it did nothing different.

Drewmeyes88

Oh and when I check for the leaky injectors do I need to get to gaskets for the plenum? And I smelled the line off the diaphragm I think it was it had a hint of gas. I forgot to open the butterflies up and smell in the tb.

skibum2100

I would take it to a shop as a last resort. Often times the mechanic will be checking boards just like this one for a solution. We can do just as good of a job, with enough effort.

You get real-time data from the ECM and it is displayed on your laptop screen, very cool. Some "tuning" programs may have the data logging abilities, I don't know.

The factory computers in these cars can't be "tuned," in the strictest sense of the word. The ECM can NOT be "flashed," like newer cars; they require a new chip. Some chips can be re-writable, some are one-time use. Check out this link about tuning these cars...

https://www.thirdgen.org/forums/diy-...uide-book.html

The fuel pressure test can further look for leaky injectors without tearing into the top of the intake. You will need new gaskets for the TB, plenum to runner, and runner to manifold. These are available from most parts stores, but it may be better to get an intake manifold gasket set with multiple gaskets in it. Note...when you reassemble the plenum/runners, coat the gaskets with vaseline to make them reusable (they are expensive).

TPS at .54V is bang on the money.

Timing (from the factory) should be at 6* BTC

What do you mean, "it was saying the timing was off and it wasn't advancing?" Timing is advanced electronically, via a small Ignition Control Module (ICM) under the distributor cap.

Did you get a chance to look at the CTS yet? Use an digital volteter to measure the ohms (resistance) of the CTS when cold and hot, the two values need to be different. You could even monitor the resistance as the engine warms, just to make sure the sensor doesn't "jump."

Make sure that the connector above the heater box is connected. It is a single brown wire to a single brown wire. If this isn't connected the engine wont run great. It is only disconnected when setting the timing.

Hope this helps.

Drewmeyes88

Well ok I will buy those gaskets this weekend and try to test the injectors for leaks. I just don't understand how that would make it cut out like that? But thank you for the advice I will try that for sure. I forgot about the cts, what wire do I put the volt meter on? How can u tell if the o2 sensors are bad or the iac? When I get that program will it tell me if those are bad?

Oh according to the vacuum gauge the engine retards it's self at that one miss. We through a timing light on it and it just moved back and forth. And that wire is hooked up I made sure.

Thanks for your help I hope we can figure this out !!

skibum2100

Unfortunately this WinALDL program doesn't diagnose the problems for you, we have to look at the raw data and decide where the problem is. It requires some interpretation, but it usually works out. For instance, another member's CTS was stuck at one value (no matter the temp) and the scanner shows the values for all the sensors. He saw that one value never changed and figured that the sensor had failed. It solved his problem.

You can test the CTS by measuring the resistance (ohms) over the two pins on the sensor, exposed after removing the connector. There is an entire table of expected values vs. resistance, somewhere on these boards. I use the WinALDL program to monitor the CTS.

The O2 sensor wire should have .450V when the sensor is NOT connected. When connected the value will vary between 0.1V and 1.0V.

I wonder if something is going on with your ICM, did you keep the original or switch it out with the new dist?
Hope this helps.

Drewmeyes88

Ok so I guess I have a update. I replaced my transmission and heater core since my last post. Well after i replaced the heater core the hesitation stopped. But to change the heater core I had to unplug the computer. So i wonder if it was just getting condensation in it?