Z28_1991_Camaro

I just finished swapping my 305 with a 350. I started the engine up today and it started with no trouble. I adjusted the timing, filled my coolant and all that stuff. The car probably idled in my driveway for a good 10-20 mins without any trouble. Then I took my car for a spin around the block a few times and it stalled on me and it wouldnt start up again. I was low on gas so I thought that might have been my problem. So I ran to my house and got some gas and went back to my car and filled up. The car started without any trouble so I thought that was my problem. I drove back home then decided to go fill up at the nearest gas station. On my way back home from the gas station my car stalled on me again. This time I couldnt get it started again and I had a full tank of gas. When I turn the key its as if the engine wants to start but it just doesnt. I think its a fuel related problem. Im going to change my fuel filter in the morning and see if that solves the problem. Im thinking its one of 3 things, either my fuel filter, my fuel pump or my new computer chip that i needed in order for my fuel injection from my 305 to work with my 350. The fact that my car started and ran for as long as it did leads me to believe its not the computer chip.
Has anyone ever experienced anything similar?

83Chevy__Camaro

it wouldnt run if it was fuel related, or even start to begin with, when you start changing and monkeying around with **** you just get problems.

five7kid

iTrader: (14)

Get a reading on the fuel pressure before you do anything else.

Z28_1991_Camaro

I changed my fuel filter this morning and the engine fired up without any trouble. It idled for about 5 mins then it stalled again. I started it up again and it started but it wouldnt stay running. My fuel filter was not in good shape and needed to be replaced anyhow. But when I was looking under the hood, I noticed the electrical clip that attached to my MAP sensor was broken and not connected well. I fixed that and the car has been running fine so far, however I havent really been able to drive my car much yet, I need to pass an emissions test before I can get my license plates renewed. I dont know exactly what a MAP sensor is supposed to do, but does that sound like a symptom of a MAP sensor problem?

five7kid

iTrader: (14)

The MAP sensor is critical for the ECM to properly control the engine. However, I don't know that it wouldn't run at all if disconnected.

I'd still get a fuel pressure reading. The pump could be weak, and it isn't uncommon for a weak pump to give out the longer the engine is running.

LoneStar666

i was going to say vapor lock, but then i realized youre EFI.

1989CamaroLT4

Buy a fuel pressure kit from a parts store and hook it to the engine. It is safe to run the engine with it hooked up (it threads on to a schrader valve on the fuel rail). Then watch it closely when it dies and see if the engine loses fuel pressure. If it does then you know it is something in your fuel delivery system. If it does NOT lose pressure, then it gets more complex - could be ignition or a host of other ailments. Try grounding a spark plug off the coil wire that goes to the distributor and see if it is firing when it acts up. That will narrow it down to ignition for you.

BTW, your MAP sensor will set a code if it is completely disconnecting or malfunctioning in a major way. That probably isn't your issue.

Bobby_80s

iTrader: (2)

just out of curiosity would the MAP sensor if faulty would the ECM give a check engine light?

kjvail1204

iTrader: (4)

if its idleing fine but wont run in drive you might be 180 degrees out. Check your distributor, it might the problem. I had the same problem. Other than that is it still TBI or TPI or is it carb'd

Z28_1991_Camaro

The service engine light did come on and the code was related to the map sensor. Since the map sensor has been connected securely the car has been running and starting ok without stalling. Im having trouble adjusting my timing however. The car ran fine for about 4 days then when i was on my way home from work yesterday it started idling really roughly. I adjusted the timing again this morning before i went to work, it ran fine without any trouble on my drive to work. Then on my drive home I stopped at the store, then drove home. After I left the store when I was at traffic lights the car idled poorly again. It would almost stall, then it would speed up again, then in my driveway i put it in park to see if it would stall or not, it didnt but it got close to stalling again then it sped up and the car started shaking a bit.
Is it safe to say its a timing issue I'm having now?
What I did was started the engine, unplugged the est wire, adjusted my timing to 6b (what my chiltons repair manual says), tightened the distributor again, plugged the est wire back in and was done. Am I missing something? My repair manual also says "refer to the instructions on the emissions control label" but that label is no longer available to me, what instructions are on that label?

1989CamaroLT4

OK, sounds like it isn't fuel delivery from tank to the engine, it sounds like the ECM isn't maintaining your air/fuel mixture correctly. That could be caused by a whole host of issues - a bad sensor, a vacuum leak, dirty injectors, dirty throttle body, etc. Sorry I can't help you any more, but I think it is safe to say you don't have a major issue with fuel pump or the like, just a tuning issue.

BTW, that MAP sensor code will set if the idle drops down too low - it doesn't necessarily mean the MAP sensor is bad.

Z28_1991_Camaro

I did have a new computer chip made for me from PCMforless so that my fuel injection from my 305 would work on the 350. I'm thinking that could have something to do with it.
If im not mistaken I replaced just about every sensor on the engine except the knock sensor(was still good), map sensor(was replace about 2 years ago) and the iat. I was not sure what an iat sensor did until about 5 mins ago when i looked it up online. I will replace that on monday or tuesday and see if that helps.
I used fuel injector cleaner regularly on a monthly basis when I was driving my car. I havent used any yet since the engine swap, I will also throw a can of that in and see if it helps.
My throtte body is clean, I cleaned everything i re-used thouroughly before I installed it on the new engine.
A vacuum leak may be possible, I already checked for any but didnt see any, I will look again to be certain.
I think the reason I got the map sensor code was because the connector was popping on and off as the engine vibrated. It hasnt come on since I connected it securely.

Randy82WS7

this is why i only run carb and old school HEI in my vehicles, they are reliable as heck


EFI is just a big PITA

i dont know what to recommend on this one,

thats not fun

good luck

rebel1222

Guys, I'm having sort of the the same problem.
I swapped a 350 motor for a 305 in my 88 Camaro. I’m pretty sure I have he time as close as I can get it by ear. What’s happening it this; when I start it up it idles rough for a minute, then smoothes out. However, it keeps stalling out in gear. I’ve adjusted the idle screw on the side of the TBI to bring the rpm’s to 750 in gear and 1000 in park. It seemed to work fine for a little while but after one test drive it is doing the same thing again.

I am now thinking it could be sensor related. I haven’t replaced any sensors, and the check engine light does come on. It seems like it is very close to running great but I’m not sure where to go from here. Where is the map sensor located, and what does it do?

Any suggestions?

xtremeirocz

what cam are you running in your 350? did you go stock or put something else in it?

Z28_1991_Camaro

everything on the car is stock except the exhaust system. I have a borla system, if anyone is familiar with the borla system it has different plates that adjust how much exhaust gets forced through the muffler. At the moment i have the solid plate in there so all the exhaust is going through the muffler. When I had the 305 in the car, I used to have no plate in there so nothing was forced into the muffler. Could that have anything to do with my poor idling? I was planning on taking out the plate again eventually so its a straight-through system again. It sounds bad as* when its like that.
It seems like the engine starts struggling after the engine gets up to temperature. When i adjusted the timing, the car idled the way it should have in my driveway for a good 20 minutes.

ZimGTA

Aren't the 305 and 350 Knock Sensors different?

Z28_1991_Camaro

some websites say they are different, some say they are the same, im not entirely sure.
I was going to get a new one when i buy my new iat sensor. I called up a local store here and they charge $92 for an iat sensor and i found one on ebay for $14 the guy on ebay also has knock sensors so Im going to get one from him at the same time.
I was just looking around trying to find prices and stumbled across this:

http://www.fbodymotorsports.com/inc/sdetail/7549

The description on that site is the problem Im having. I think I will get one of those while im at it.

ultimatefighter

That is what i was led to believe. I was told you have to use a 350 knock sensor.

Z28_1991_Camaro

A knock sensor wouldnt affect how the car idles would it?

1989CamaroLT4

The knock sensor is primarily used to adjust the ignition timing under load.
Shouldn't affect your idle.

Colts45s

read to sticky 305 tbi to 350 tbi engine swap the knock sensor isn't your problem sounds like a vacuum leak to me but he im going through similar probkems myself

mdurbala

iTrader: (1)

so did you ever figure this out

Z28_1991_Camaro

I still haven't figured it out yet. I'm really hoping it's just the knock sensor which I have yet to replace. I ordered a knock sensor at the end of January and I was sent the wrong one. I called up the place and told them I didn't receive the correct one. They were then supposed to send me a box so that i could ship the incorrect sensor back to them and I wouldnt get charged for shipping. I then called up a couple days later and I ended up ordering a 2nd sensor so that they could ship it right away. A few weeks went by and I still hadnt received anything from them so i called up again and the lady tells me she doesnt know why the sensor hasnt been shipped yet and she would take care of it that day. A few weeks go by again and I still havent received anything so i call again and this time the guy i speak to says he doesnt know what their shipping department is doing and that the part is on backorder and he was supposed to get it in yesterday and have it shipped out for me either yesterday or first thing monday morning. So i called up yesterday to see if he had in fact received the sensor, and the guy told me he hasnt got it yet but he will call me and keep me informed. So thats where im at right now. The car still runs the same, its fine while driving but it idles poorly. I havent tried anything else. From what I read in my Chiltons manual it kinda sounds like the knock sensor may in fact be my problem. But, Im far from an expert and it may or may not fix my issue.

mdurbala

iTrader: (1)

damn well keep us informed, im going to be doing the same swap here soon except i was just gonna cam it and maybe mill the heads to bump the compression, so how you likin it overall as compared to the old l03... also ive had problems like that with ebay cause everyone and there mom has a ebay store, all you have to do is apply for the business license pay the $500 and you can start ordering direct from manufacturer so these people are doin it for a 2nd job and are in no rush to get anything done... kinda sucks ive done pretty good with racers direct outlet, i believe thats the name i always get everything asap

Z28_1991_Camaro

I ended up ordering the sensor from Fbody motorsports. I didnt get it from ebay. The stores over here want $75 plus tax for a knock sensor, the cheapest one i found on ebay was $50 plus shipping, the store i bought it from charges $35 plus $10 for shipping and I dont have to pay tax on it. If i had known it was going to take more than 2 months to get it i would have gladly paid $75 for it.
I expected a difference between the 305 and the 350 but not as much as i got. There is just so much more behind the pedal now. I ended up getting my first speeding ticket a few weeks back because of it. I got about 1200km on the engine so im trying to start to have some fun with it. Its great though compared to what i had. I didnt want to get too carried away, if i could have afforded it i would have done a little more, i really wanted to get some headers while the engine was not installed but i didnt have the $ for it.
Its much worse in the snow though than the 305. I had an accident with my winter car so i was forced to drive the camaro since the middle of January. I didnt have a winter car last year so i drove the camaro all winter and i dont remember sliding as much as i did this year.

mdurbala

iTrader: (1)

yea we dont have the snow problem here in arizona, sounds like the swap is well worth it tho, keep us posted after you get that new knock sensor in

mxcrazed

my boat with a carb and no computer did the exact same thing after my dad changed the distributor from a points and condenser to an electronic he did this at the same year as switching from a 305 to a 350 he ended up getting a new distributer i think that maybe you guys have an issue with your distributor or possibly a hardness issue with the cam gear if you switched to a flat tapped from a roller or visa versa i have a feeling im on to some thing ill ask my dad more

Badass355ciz28

iTrader: (17)

did you check for spark after your engine died? might be a coil over heating or a bad magnetic pickup or ignition module

mdurbala

iTrader: (1)

still no fix?

Z28_1991_Camaro

I installed the correct knock sensor today but it didnt fix my problem. The idle is still not what it should be.
Also, lately when I first turn the car on and put it in reverse it will stall sometimes. I have an automatic transmission, cant afford to go manual just yet. It happens maybe once every couple weeks. Another thing it's been doing is when the engine is up to temperature if I change from park or neutral to drive it gives a good firm jolt. You shouldnt feel it when you go from park to drive am I right?

Bobby_80s

iTrader: (2)

i have that too, i heard its due to the high idle for the big jerk or jump when you shift.

mxcrazed

it may be worth looking into looks like more than a coincidence