tpi81

ran codes on my 88 350 TPI it showed
33 MAP Sensor Voltage (HIGH)
36 ignition system circuit error

what do I need to fix this!!! Know how to get the codes just not what they exactly mean!!

Rolling Thunder

First off the code 33 for your year means the MAF reading is too high your year dosnt have a MAP sensor. So anyways a more detailed look at what these codes mean would be a good place to start.

Code 33

As stated it means that the ECM has seen a airflow reading that is unreasonably high. For example if the motors not running but the sensor is still reporting air flow of over 45 grams per second that doesn't make scene so the ECM throws a code 33.

Code 36

Long story short MAF sensors have a self cleaning cycle they run through after the car is shut off. What it does is is briefly apply voltage to the sensor wire to make it glow red hot to burn off all the carbon and anther impurities. A code 36 is set when the ECM does not detect that this burn off sequence happened.

Now what to do? Lets start with the 33. First ide disconnect the battery and reset the codes to see if this is an intermittent problem. Next Apply 12V to terminal "G" on the diagnostic port with a jumper wire. Terminal G is the pin on the bottom row first pin on the left side. What this does is fire up the MAF circuit so we can check to make sure its getting power. Once this is done disconnect the MAF sensor and measure for voltage on the red wire in that connector you should see 12V. Try that out and we will go from there.

tpi81

1 more thing to ad is the MAF sensor is off and won't run right when its on it!!! Sorry forgot to mention that!! And whats terminal G the way I checked the codes is with a paper clip!! Today I Hooked a vacuum gauge up to the vacuum line that runs from the throttle body and it stayed around 20 on the guage and drops when you press on the gas?? What causes that?

Chevy86 IROC-Z

iTrader: (17)

Code 33 fix. Get a dremel tool and clean off the contacts in the wiring harness and in the MAF sensor. Make the pins and the female connectors look shiny. This makes better contact and it should fix your code 33. If not, then the MAF is bad.

Rolling Thunder

When you say the MAF sensor is unplugged and wont run right when its plugged in? If thats the what you mean im not really surprised because if the MAF sensor is sending BS reading it will make the car run bad where as if its unplugged the ECM recognizes this and runs off default values instead of sensor data allowing it to at least run though not well. However this will also cause a code 33 to be set. I would plug it back in clear the codes and try again and see if the code 33 still exists. Terminal G is in that same connector where you jump the 2 pins together to ring codes out but instead of the upper right 2 you need to jump +12v to the lower far left pin also known as pin "G". Jumping 12 V here will activate the MAF power relay or should and from there we should be able to see if the MAF sensor is getting power as a place to start anyways. As for as the vacuum reading is concerned with the throttle blades closed air cannot flow into the the intake fast enough to equalize the pressure developed in the plenum resulting in vacuum being developed. However when you crack the throttle more air can flow in to equalize the pressure causing your vacuum gauge reading to drop.

tpi81

Thanx man your a pretty fart smeller LOL Thanx for the help and will test the MAF sensor thanx!!

Chevy86 IROC-Z

iTrader: (17)

I got a far more better way to troubleshoot your MAF Sensor. It's far better than anyother advice and it's dummy proof. Do you want it???? Of course you do. Well then here you go buddy.

This is by far the best troubleshooting method for our MAF sensor for our TPI.

street_carnage

ummm, relays?

ASE doc

Rolling Thunder is right on the money!

Chevy86 IROC-Z

iTrader: (17)

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Chevy86 IROC-Z

iTrader: (17)

tpi81,,,, whats the situation? Give us an update.

tpi81

Sorry guys been busy!!! Haven't had a chance to check it yet sorry!!! Been doing a lot lately with work and all will test it tomorrow!!! Sorry for the long delay!!

Chevy86 IROC-Z

iTrader: (17)

No problem tpi81. Be sure to use the troubleshooting paper that I sent you. Also keep in mind, do what I mentioned on post 4. I had the same issue. Once I cleaned the male and female connectors, my "33" went away.

tpi81

Ok cleared the codes and 33 nor 36 showed up??

tpi81

Ok even though the codes aren't showing now I'll still clean them up they look a little dirty!!

Rolling Thunder

If you cleared the codes, drove the car around a bit, and neither of the codes has returned you probably have an intermittent problem. If this is the case I would proceed by checking and cleaning the connection at the MAF as mentioned and also the connections at the MAF power and burn off relays. Once thats done I would drive it around and see how it goes. If the do not return great if they do let us know and well have to dig a little deeper. Since the codes have cleared have you noticed any drive ability issues?

Chevy86 IROC-Z

iTrader: (17)

. Another thing to check is the insulation at the 2 most important relays, MAF Power Relay and MAF Burn-off Relay. The insulation is NOTORIOUS for sagging down with time. Just make sure that if the wire is exposed, find a way to keep them from touching, If you have money, go here to buy a new replacemnet set,

1. http://cgi.ebay.com/ebaymotors/ws/eB...d=370136178191

2. http://cgi.ebay.com/ebaymotors/ws/eB...d=370136177890

It would also be wise to use dieelectric grease IF the weather pack insulation inside the connector is bad or corroded (look at picture in your not sure what the weather pack isulation is).

tpi81

Ok talked to a guy he said he thought it might be the crank sensor and I also happened to talk to my great uncle that I haven't talked to in a while and he said back in 1990 he bought 2 cars one had a 305 tpi and the other one had a 350 tpi the one with the 350 had been wrecked and he had to have the crank replaced in it. Now he can't remember which engine went into my truck and I'm wondering if there couldn't be a connection between the mans thought about the crank sensor and what my uncle said. Now is there a chance that when replacing the crank could the mechanic have not hooked up or did something to the sensor to make it not work right now late last year when I got the truck we had problems with the backfiring and stuff it hasn't done it in a while but could that be whats wrong. If it isn't then I'm going to throw a carb and intake I got laying around on it. Any help will be greatly appreciated.

ASE doc

tpi81, The TPI motor doesnt have a crank sensor. Cam position is monitored by the pick up coil and reluctor ring in the distributor.

John 89 Formula

I would change the relays before I did anything else, and as Chevy pointed, out check the condition of the wire harness at the relay plugs, and insulate any bare wires.

Chevy86 IROC-Z

iTrader: (17)

Back fire? that may because the timing is off or something is failing inregards to the ignition system. When I rebuilt my engine, I could not get my engine to rev above 3,000 RPM's. It would backfire like crazy. I then decided to replace ALL the guts from the dizzy. Come to find out, the magnet that is just above the pick-up coil was cracked. When I replaced the pickup coil (magnet included), I was . In other words, the issue may be with your timing/ignition. There are a few possibilities to backfires, but it has absolutely nothing to do with the trouble code 33/MAF sensor. Even then, if it was the MAF sensor going back, you would have hesitation issues followed by poor performance as the ECM switches over to its default mode.

tpi81

Performance is good when it runs drove it a little today and its started that dying but then would crank right back up. And it hasn't backfired in a while was just going to mention that it had done it before but I'm changing it over to carb because I need something to drive to school this August. It has had these problems and I have done put to much time/money into it. But I still need yalls help about the dist. will it work on a carbed vehicle how could I get it to work and the intank fuel pump could I buy a regulator to get it to work with the carb.

ASE doc

Im sad that youre giving up on your TPI. I understand though that without a good background in computer controlled engines, these can be tough when they act up.

In answer to your questions. No, your EST distributor will not work with a carb. It requires the ECM for timing control. Good news is that this is a small block chevy and there are many distributor options you can go with. The simplest is probably old school HEI with internal coil and centrifical advance.

Yes, your in tank pump will work with a carb. You will need a bypass regulator to maintain pressure at 4-6psi. Personally though, I prefer to dump the high pressure in tank pump, replace it with a pick up tube that you can make yourself from steel/rubber tube, install an external low pressure fuel pump thats easy to service. Be sure to install a filter before the external pump.

Chevy86 IROC-Z

iTrader: (17)

tpi81, Im with ASE doc. Once the TPI system is operating properly, It gives good performance output and most importantly, since the car is your daily driver, it's very economical as in fuel. Im not familiar with carbs. Checkout these threads,,

1. https://www.thirdgen.org/forums/tpi/...t=convert+carb

2. https://www.thirdgen.org/forums/carb...t=convert+carb

Greasyleo

I need help. I have a 1988 chevy 305 tbi. Now it's a farm truck I'm trying to bring back to life. I got her on the road and running but I have some problems and I need some help. I have put new plug and wires with cap and rotor, I changed the map sensor, o2 sensor and the temperature control sensor going to the ecm. Now everything I done has made the truck run sooo much better but I have a rough idle and it seem to just bog down and die likes it's flooding itself out. They chopped the exhaust on the truck and straight true duals to glass packs on both sides. It sounds mean and I know that could be part of the problem I think. I keep getting a 33 code and all my lines look great and I can't blow through any lines when the other side is plugged so I know my lines aren't cracked and sucking in air. Please help

Tony Sanchez

"you need to jump +12v to lower left pin also known as pin "G". How do I go about doing this? Do I run lead wire from the battery to the G pin?
Thanks,
Tony