My 88 350,tpi has a problem that's driving me nuts. It's hard to get started. If you do get it to start, the idle is terrible. check engine light comes on. It gives me code 12,34. I tried hooking my scanner up and get an error msg. So i get out my jumper wire and get the codes. Funny thing happend I accidently started the car with jumper wire in place. It ran fine!!! I will check out the maf sensor. Does this make sense to any one? Why will run fine in field test and not out? HHHHHHHHHHeeeeelllllllpppppppppp!!!!!!!

 

I believe a code 34 is for the MAF sensor. Before you replace the whole sensor, try and replace the MAF power and burn off relay.

 

Bump -- I have the same problem but im only pulling a code 12 i think it means you ecu has a bad power or ground it its friend. but mine has a hard time starting i have to use starter fluid and it idles like ****. but somone also cut off my maf plug out so i donno im waiting on gm for a new plug and ill talk to my shop teacher about the code 12 tommorw.

Any more information would be helpful.

I have the 89 iroc 5.7 tpi so everyone knows :0

The whol car starting fine with the jumper wire in almost(dont hold me to it) sounds like your not gettin power to your ecu and when you had it jumped for codes it was now gettin power.... Maybe?

 

A code 12 is normal.

 

big you timing is off... have you changed plugs or dist cap lately...
you too gray both of you throw a timing light on it and have a look

 

Thats all stuff im not going to check yet i want to get the MAF hooked up first im just waiting on Gm they said friday morning for the new plug im hoping my maf unit is still good But Im going to do a full tune up and timing all of that in about 8 days. I found out my ECM fuse had blow too i just replaced it about an hour ago.

When i bought it the fuel pump was rigged to a switch aswell as the fans and guess what the pervious owner knew how to bypass a relay but didnt know how to check a fuse... So im one step closer now i know the MAF is going to help out alot i need to get this thing back to optimum

 

well do you have a SES light on when the car is running?

 

Yes my SES Light is on all the time it only turns off when you turn the key off. But any who its rading a code 33 high voltage low vac from mass which would be right cuz i dont have a mass or plug for the mass on it right now. its still reading code 12 but somone said thats normal.

Any one know what amps the fuse is supposed to be for the ecm by the battery mines blown 2 20 ams no so i have a 30 but i donno whats really supposed to be in their

 

if you are blowing fuses like that STOP PUTTING THEM IN! thought that would be obvious... now you arent blowing the fuse under the dash? which is very odd as that is a 10 amp fuse so smaller than the 20 would blow first... if your putting 20 in the ecm blade fuse under the dash DONT that is only supposed to be a 10 if you put more than that you Will damage your ECM...

Or are you talking about the fusable link from the battery to the ignition circuit? well stop replacing those also you need to fix the problem before you seriously damage the car any further...

so which instance are we talking about

 

The fuse under the hoof for ecm and fuel pump. its supposed to be a 20 amp i just found that out but it blew on hard acceleration randomly after a day and a half od hard accelerating and it was fine. so im thinking it might be a wire shorting out... but any more info will help. Im going to look tommorw in autoshop aswell. Are their any relays, pumps/ switches that could blow this fuse?

And i only blew one when i got the car it had a blown one so i replaced it 2 days ago and it just blew today so i i get to find the problem... Atleast im on the right track.

My car has no MAf what so ever the owner befor me cut the wiring for MAF and everything out so i dont think that would blow the fuse tho.

 

well that one fuse protects the whole electronic fuel system and the entire MAF system the oil pressure switch the cooling fan and probably a bunch more... so if you have a hardwired fan(very stupid and useless) that might cause the link to blow or as the MAF has been "CUT OUT" i would suspect that those wires are shorting and this would stall the car or prevent it from starting but it would deff be in the MAF electrical and has nothing to do with hard eceleration

and how do you know it is supposed to be 20 amps? as there could be much more load than that with all of the systems this would run... and this connector doesnt allow for switching fuses it is a replace only item

 

I just check a wiring diagram its 20A for shure so no i know i have a problem somewhere probably just a rubbed or burnthrough wire groudning out...

Yea im aware of the systems it runs but i think the only way to bloe the fuse would be a short or something drawing to much power so im deffinatly going to look at the wiring and see if their are any bare wires.

 

So i just got my MAF wiring all hooked up and plugged it in and its didnt really chaNGE ANYTHING.

I start the car 350 TPI 89

And it starts right up, idles high like 1500 then slowly drops down to 1000 idles smooth then 10 seconds later it drops to 500 and throbs from 500-900.

I fixes 2 vacume leeks and its still doing this.

Ive got a code 34 high vacume i think. So i unplugged the maf and it made no difference in the cars idle plugged or unplugged. Im pretty shure my relays are good im gettin 13.-- at red. And on either blue or red i was gettin around 9 i beleave with the car running at idle...

 

i was under the impression that a maf maxxed out at 5 volts...

 

i just did some more research...

green wire is supposed to have between 4 and 6 volts key on any more or less their is a problem...

sorry got ahead of myself

 

my fuel pump fuse is a 15amp is that correct? you say yours is 20amp?

what would a lower value do to the electrical system?