Need help, code 33 on TPI w/ MAP run bad

[40_Tudor]

My 40 Tudor with 87 IROC 5.0 TPI would not start the other day. Check.. no spark. 12 V  to coil and distributor control module.  Pulled cap, contacts on pickup coil was green. No resistance on ohm meter. Got new pickup coil, Jeg's Excel module and coil. Set timing @ 6 deg with brown wire disconnected.
It runs but * when accelerating and misses above idle. Code 33 at ALDL. No vacuum leaks to be found.
This has been converted from a MAF to a MAP sensor when I built it over 5 years ago.
Ran fine before pickup coil went out.

Any suggestions?

[enjenjo]

Check with this chart  http://chevythunder.com/maf_code_33.htm  It's a MAP sensor code, my guess you have a broken or disconnected vacuum line.

[wayne petty]

My 40 Tudor with 87 IROC 5.0 TPI would not start the other day. Check.. no spark. 12 V  to coil and distributor control module.  Pulled cap, contacts on pickup coil was green. No resistance on ohm meter. Got new pickup coil,
Ran fine before pickup coil went out.

Any suggestions?

pull the cap and rotor back off... use a bright flashlight to look down at the top of the reluctor on the small cap HEI shaft...

see if its cracked like this..



why would this effect anything..

so we have a cracked magnet on the signal generator armature..

~~~~~~~^~~~~~~~^~~~~~~~^...  so it creates a random or ghost waveform in the pickup coil..  below 400 RPM the electronic spark control is NOT active.. above and with the tan wire connected it is..

disconnect the tan wire again.. see if the engine runs better..  i know what a chore removing the cap and rotor is on a TPI motor.

electronic spark time when engaged looks at the AC wave form.. and instead of opening the power transistor as the tips of the reluctor align with the tips of the pickup coil it keeps a timer going..  shorting the delay from the pickup coil passing zero going negative event.. to open the power transistor to trigger the coil...

if it shortens the delay.. it advances the timing..

if it lengthens the delay.. it retards the timing..

the ghost patterns in the wave form trigger random count downs and out of phase spark events. .this causes weird running of motors..

please also examine the sides of the ignition coil...




this has most of the info you may need..

http://forums.superchevy.com/corvette-fever/70/8585187/c4-corvettes/which-used-scan-tools-for-82-to-94-corvettes-with/

[40_Tudor]

Thanks for the tips Wayne and Enjenjo. I'll do some checking this weekend and let you know what I find.
I need to find an older OTC scanner for my OBD I ALDL.

[bucketmouth]

Hey Darryl when I was over your way last year I bought a INNOVA OBD1 scanner for my 5.0L EFI 34Coupe I also bought over there as we don't have then here in OZ.
It proved invaluable in diagnosing my engine problems. However while using it a little while later the engine stalled while carrying out an KOEO test damaging the scanner. The screen now flashes on and off continuously rendering it useless.
I hope you have better luck if you buy one.

[wayne petty]

Hey Darryl when I was over your way last year I bought a INNOVA OBD1 scanner for my 5.0L EFI 34Coupe I also bought over there as we don't have then here in OZ.
It proved invaluable in diagnosing my engine problems. However while using it a little while later the engine stalled while carrying out an KOEO test damaging the scanner. The screen now flashes on and off continuously rendering it useless.
I hope you have better luck if you buy one.

innova will fix those usually...  would you like contact info..

http://www.innova.com/

http://www.innova.com/en-US/support/ProductSupport

is this the version you bought for ford EECIV

http://www.innova.com/en-US/Product/Detail/0b8de87a-0bfd-4bae-aed5-4eac63c4a0a4

i had a similar thing happen to my autoxray.. but the wiring harness was shorted out and the owner turned on the key to roll up  the windows when i ask him to come out and disconnect the battery.. as i had my fingers separating the wiring in the harness.. i ended up opening and just carefully resoldering my unit.. and it works again..

please print and perform this test on your ford before you plug any scan tool back in.. and since its eeciv.  look at the harness near the computer connector..  you will find that there is a pair of wires sticking out with ring terminals.. those must be properly grounded to the body.. and the engine properly grounded to the body as is proved on test #4  
http://i.imgur.com/WMDprhm.jpg

you can actually use an analog volt meter.. one with a needle to read ford codes..  this is me getting codes out of an 83 cressida with it.. and the reason you need an analog volt meter.. as the space between the numbers is 2 volts or so... its impossible to view the pulses and figure out what they mean with a digital volt meter.. i know i tried..

[40_Tudor]

Update on code 33 problem.
Checked distributor magnet for cracks, looks good. New Eccel coil and dis. control module. Put old GM coil back in, not difference. Idles OK, runs fast OK, normal starting out...not so good.
Tested MAP sensor voltage, 5v going in, 5v out on center lead. Went to store and picked up a vacuum pump. Test lead on center lead, 5 volts no matter what pressure is. Pumped down to almost 0 and still had 5v. Going to pick up an Echlin 1 bar MAP sensor this weekend.
This should be fun.
Guy behind counter. What year and model car do you have sir?
Me...1940 Ford.
Him... My computer doesn't go back that far. I didn't know they had MAP sensors back then.
Me... Well the motors out of a 87 Iroc.
Him.. Well that has a MAF sensor
Me... Not any more.

I found 1 guy down here that speaks hotrod but its at AutoZone and I'm not going to put in Taiwan ignition parts.

Supposed to rain for the next week down here so not sure when I'll get to drive it. Not very water tight yet.

[wayne petty]

Update on code 33 problem. Tested MAP sensor voltage, 5v going in, 5v out on center lead. Went to store and picked up a vacuum pump. Test lead on center lead, 5 volts no matter what pressure is. Pumped down to almost 0 and still had 5v. Going to pick up an Echlin 1 bar MAP sensor this weekend.

check grounds...

pin C  wire to pin A wire should have 5 volts..
Pin C wire to pin B wire should vary..
pin A to B should also vary in the other direction from C to B.

PIN A wire to the negative battery post with the key on should be really close to 0.00.. but NOT exactly ZERO.. flip meter to 2 volts DC and you should see a fraction of a volt.. 0.02 or so..  i worry that you have lost the ground.. no ground and you will get only 5 volts out of everything..



if you loose the ground..  there is 5 volts all the way across the resistor in the map sensor..

with a ground. you have 5 volts on one end.. and almost zero at the other.. so the variable wiper.. can select how much to send back..  this is a solid state unit but it works very much the same way.

there are two or more individual ground connections.. to the computer.. they must ALL BE PROPERLY hooked up to ground on the engine block/heads

sample.. these are from a vortec astro van

http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/gm%20TBI/CAM00506_zps776ccec1.jpg

http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/gm%20TBI/CAM00505_zps8ee7b05a.jpg

http://i1207.photobucket.com/albums/bb476/waynep712/corvette%20diagrams/85TPIvoltagepinout_zps9b30f316.jpg

http://i1207.photobucket.com/albums/bb476/waynep712/corvette%20diagrams/86turbobuickECMpinout_zps4c3c64ec.jpg

i am not sure if these last two are the proper connectors for your computer. they are close..

you can see how the ground and power wiring are shared on some models this is for a LT1 version slightly later.. look at the lower left corner..

http://i1207.photobucket.com/albums/bb476/waynep712/corvette%20diagrams/92_95_C4_VIN_P_enginecontrolwiring_zps4926633d.jpg

in the lower left corner and in the upper center. B is actually ground.. and what is confusing is with the air temp sensor and the engine coolant temp sensor.. the other wire is 5 volts..  the variable thermistor varies the connection to the GROUND WIRE for the 5 volts.  the computer has a Current limiting device on the 5 volt regulator for that circuit.. and it looks at how much voltage is NOT sent to ground to use for the calculations.. way different.. kinda a twist on voltage drop.. very creative.. and it works really well.. if you unplug the sensor. the voltage goes to 5 volts and the computer things the temp is -20F..

can you PM me with  which craigslist you use.. there are several in ohio..

http://www.craigslist.org/about/sites

[wayne petty]

This should be fun.
Guy behind counter. What year and model car do you have sir?
Me...1940 Ford.
Him... My computer doesn't go back that far. I didn't know they had MAP sensors back then.
Me... Well the motors out of a 87 Iroc.
Him.. Well that has a MAF sensor
Me... Not any more.

I found 1 guy down here that speaks hotrod but its at AutoZone and I'm not going to put in Taiwan ignition parts.  

you really need to have one of the eye glass cameras on when doing this..

or the cell phone in your shirt pocket turned on and aiming out over the lip of the pocket when you go in and ask for parts..

hint.. look up parts online by fuel injection application.. then ask for them by number ..

this helps sometimes in parts look up.. as some of the duralast stuff is wells

http://www.wellsve.com/parts/



i ask if the local autozone had any bags of oil absorbent when a oil filter became the exxon valdez in a friends driveway.  the Autozoner kept asking what weight oil i wanted.. i keep saying i don't know.. it comes in a big paper bag..  i even said cat litter like stuff.. he told me to go to the grocery store.  you should have seen his face when i walked in grabbed a bag from the display in the front window and dropped it on the cash register counter in front of him..  he had never seen or sold that.. did not know what it was or what it was for..  at least all the out door cats did not run up and roll in it like happened last time i poured out a big bag of it on a 50 foot oil streak from a blown filter. .

[40_Tudor]

Wayne,
I'll double check the readings this weekend before I go to the parts store. I checked the grounds the other day, never hearts to check them again.
The shop I used to work in we had several test MAP sensors we used just to test the circuit. Wish I had one now.
I have a home in Columbus Ohio but I'm working a contract job in Lexington, KY making technical manuals for military ground vehicles. I do the exploded views for the manuals.
I've never use Crags list or face book.

I'll let you know what I find out this weekend.

[wayne petty]

Wayne,
I'll double check the readings this weekend before I go to the parts store. I checked the grounds the other day, never hearts to check them again.
The shop I used to work in we had several test MAP sensors we used just to test the circuit. Wish I had one now.
I have a home in Columbus Ohio but I'm working a contract job in Lexington, KY making technical manuals for military ground vehicles. I do the exploded views for the manuals.
I've never use Crags list or face book.

I'll let you know what I find out this weekend.

this looks like it might have the right stuff.. its 150 bucks but it will also do a lot of import cars.. or ebay the extra stuff..

http://louisville.craigslist.org/ele/4657226005.html

[40_Tudor]

Wayne,

I rechecked the streetrod today with your cheat sheet.
Here's what I got:
Key on, test probes in connector with MAP connected. Meter set to 20v
A to B = 0.56v
A to C = 0.10v
C to B = 0.67v
Vacuum applied "no change"

Key on: A to engine ground = 4.90v
Key off: A to engine ground = 0.000v "varies a little if I tap meter or probe ~ 0.006
A to ECM plug, MAP disconnected ECM plug disconnected,  (ground wire MAP plug end to ECM end of wire = 7.65 ohm. Key off Checking continuity between plug on MAP and ECM. Same reading no matter where I ground second probe from MAP plug to ground.

[wayne petty]

change map sensor..

did you see this interesting write up over at wells


http://www.wellsve.com/ds_map.html

won't help you diagnose your issue..

for a 90 camaro 5.7
http://www.wellsve.com/parts/index.php?PART_KEY=000663767&PART_NO=SU105


http://www.wellsve.com/custom_searches/showpinoutdiagram.php?partno=SU105#zoom=100

ahh.. this is what i was looking for..

http://www.wellsve.com/custom_searches/pdf/sales_drawings/SU105.PDF

it shows the voltage verses vacuum output..
just to save you some calculations if your vacuum gauge is not marked with both calibrations..
20KPA is about 6 inches of mercury
55KPA is about 16.25 inches of mercury
85KPA is 25.1 inches of mercury.


wow... and what a win by baylor..

[40_Tudor]

I rechecked all of the grounds, put an extra ground on ECM case to body, still no change in readings when vacuum is applied. The MAP sensor was used one we had in the cabinet at the shop I used to work at. I think I'll pick a new one at NAPA and see if the readings are any different. I need to check on that OTC you sent the link for too. If I where back home I could go into the shop and barrow the one they have. 250 miles away presents problems.

More updates to follow.

Joe

[40_Tudor]

Put in an new MAP sensor and it still runs bad, maybe worse.
Pulled dist. cap back off, got bright light, magnifying glass and found some small cracks in the magnet around the shaft.
Going back home this weekend I'll stop in to the shop and see if I can find another distributor and try it. One with out cracks.