On my 88 formula 305 tbi/auto my ses light has been coming on. I am running a code 34 constantly. From everything that i've read that is my map sensor, right?

My car takes long cranking to start usually 6 secs on first try with no start, then crank right again for about 3 secs, starts, dies and then starts right up again and runs a little rough at first then ok. It drives fine down the road, but seems to run a little rich.

Where should i start at? Does the Map have a relay to replace like the TPI cars with MAF?

Thanks, i have very little experience with TBi, brad keith

 

First thing I would do is verify that your vaccum line from your TBI to your MAP is making a good seal and/or not damaged. Should be a small hose from the back of the TBI to the MAP that is mounted on a bracket on the firewall on the passenger side. Other than that, the sensor could just be bad all together. Plus I would listen close if you can and make sure you don't have any vaccum leaks either.

Tom

 

Tom has it nailed.

Long cranking, high MAP (low vacuum), error codes - you may have a vacuum leak. Check hoses, the PCV, brake booster, gaskets, leaking EGR, exhaust restrictions, air filter condition, etc.

 

I am pretty sure there are no vaccum leaks in the system. I ran over all the vaccum lines already and found nothing broke or loose. My next step is i might just replace the map sensor

 

BK,

A vacuum gauge might be very helpful in diagnosing this problem. If idle vacuum is low, the sensor is only telling you what it is sensing.

The protracted cranking before start is an indication that you may have a vacuum problem. You might also want to take a peek at the TPS voltage.

 

I was planning on hooking my vaccum gauge up today or tomorrow, just to make sure i didn't miss anything. Could you enlighten me a little bit on checking my tps voltage? i have little knowledge of the tbi. THanks. brad

 

Brad,

The vacuum reading should answer a lot of questions. As for the TPS, connect your digital voltmeter probes to terminals 'A' and 'B' on the connector. (‘B' is the positive connection, ‘A' the signal ground, or negative.) Probe the connections on the TPS electrical connector using sharp probes entering the back side of the connector (back-probing).

About probes: If you have very slender probes on your VOM, you can back-probe the TPS connector while it is attached to the TPS. If you have larger probes, you can make connectors from large dressmakers pins or a similar item. With these, you can back-probe the connector as well.

Turn on the ignition (engine off) to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.

If you can't find the TPS, this might help: