I need (well actually my car needs) some help. I put in a 350 tbi and it runs BUT it surges and hesitates and if I give it too much gas it will stall. I have new plugs and wires, I'm going to put on a new cap and rotor, will that help?
also the knock sensor is getting replaced (the wire that connects it to (well what does it connect to come to think of it) is gone.
thanks in adavance
Adam

 

keep in mind the knock sensor for a 305 and 350 are different, with that being said lets go through a few basics so people might be able to help you a little better. What is your timing set at? How much total advance are u running? Are you running the stock 305 tbi setup? Stock chip or a custom burn? what size injectors are you running?

 

the timing is set at 2* btdc, not sure about the total advance. I'm using the stock 305 tbi and chip. thanks for a timely response I'd like to fix it up tmorrow at school if I can figure out what it is tonight.

 

any fuel pressure readings?

 

Seems like it is running lean.
1. Check fuel pressure;
2. Fuel filter might be clogged;
3. Fuel pump is dieing;
4. Injectors are clogged.

Sometimes spark plugs can cause same failures.

Does it show any code?

 

thanks for getting back so quick. where would I put a gauge in to check fuel pressure? I'm going to change the filter tmorrow, the fuel pump is only a few years old and I didn't have this problem with the 305. the spark plugs and wires are new. the injectors look ok, at least they look better than the ones that came off the 350.

 

Correct me here if I am wrong. I don't think there is such thing as 350 TBI. So you are using 305 TBI setup on 350 engine. Is it correct? Therefore the injectors might not have enough flow.

 

you are right, the 350 tbi didn't come in my car stock, I got it from a junkyard it came out of a half ton pickup. as for the injectors I have talked to a few people (including holley) and everyone thinks it will work ok (not great, but ok)

 

ECM thinks that it is working with 305 engine. It is trying to supply fuel accordingly. Besides the fact that something else might be wrong this one by itself will cause hesitation.

To fix it the right way you would need new PROM for TBI 350 which probably does not exist. The easiest fix would be to adjust the fuel pressure slightly higher than in 305 system.

This is the first step you might try. Unfortunately I am totally unfamiliar with TBI system. As of where components are located and additional troubleshooting guides you can check Autozone's web site. It's quite impressive what they got in there.

 

I know I need a new chip, jet has one off the shelf but I'm constantly hearing that its better to burn my own (but I don't have a laptop, I know very little about computers, and have to much other junk going on to learn how to do it). where would I put a fuel pressure gauge in to check fuel pressure? and where does the wire coming off the knock sensor go? (could this also be part of the problem?) also my car wasn't doing this at first, so if the chip was going to cause that problem wouldn't it have happend right away? one last thing, how do I turn up the fuel pressure? do i have to get a AFPR?
thank you much

 

My car is TPI. So it's out of my league now. I'll let you know if I find anything else.

Guys with TBIs, can you help him out?

 

it should be able to run fine with the tbi setup off the 305, the 350 chip does exist and is probably in the truck you removed the engine from as 350 tbis were quite common, just not in f-cars, you said it ran good at first, how long was that for? I'm beginning to think your problem lies in the knock sensor as it controls timing retard/advance, fix that first and see how it runs. As far as where the wires are located for it I believe they are in the same harness as the wires for your smog pump, but I could be wrong, do a search or maybe a more knowledgeable member will chime in, I've never owned a stock 3rd gen, or a injected 3rd gen for that matter....

 

I replaced the fuel filter, air filter, cap, and rotor and that helped quite a bit (so did a full tank of gas i bet). tmorrow the new knock sensor goes in, the 350 knock sensor is in the block but I'm not sure how well it works if at all. I emailed tbi chips and the guy said he can burn a chip that will help. also he said that I need the 350 injectors but I'd just like to get the holley 670 tbi (opinions?) and an electronic spark control module, what is that, how much is it and where does it go? thanks for all the help thus far and keep it coming

 

should be on top of the dist cap, as far as the custom chip, if it is a bone stock 350 truck engine you could simply go get the chip from the truck it was in assuming its compatable with your ECU, and save a lot of money, then buy a custom chip after you do some mods (good mods for that engine would be heads and a cam since the swirl port heads that are most likely on it are pure junk, a set of ported 305 heads with some larger valves would be real nice, if you still have your 305 laying around you might want to consider pulling the heads and working them over) anyway sorry about the long post, let us know how everything works out, I would suggest unhooking the battery for a while after replacing the knock sensor to make it relearn and let us know how you make out, glad to hear your getting somewhere

 

I thought about using the chip from the truck it came from and I asked an auto insutrctor (at the college I go to) about it and he said not a good idea because the timing curve and fuel delivery demnds are different. do you think the knock sensor could be causeing part of the remaining problem? would advancing the timing 2 or 3 degrees help any? what would I be looking for when looking at heads? I don't know about a cam it seems like a pain to install I'll just do it when I pull the motor back out in the distant future. is the holley tbi a good idea? holley thinks it will work but then again they might just be trying to make a sale.
thanks for the help and keep it coming.

 

Someone should really move this to the TBI forum for you. There's alot of guys there who have done what you're doing, and I almost did it also. I sold the car instead. But I have had both a 92 RS and a 89 C1500 with a 350, so basically I have visuals of what you're talking about.
You need to use a 350 chip. I don't believe the computer from the truck is the same, but if it is, meaning the chip fits, it will have the one you need. If not, then a 350 TBI caprice will have the right chip for you. Think about what your shop teacher is telling you- the timing curve and fuel delivery demands of the truck is different for the 350 truck as opposed to the 305 camaro. But you are using the engine from that truck. Therefore, you need the chip from that truck (or one like it).
You should also get the fuel injectors from that truck, your 305 injectors won't work as well as the 350 ones will. Even if you change the fuel pressure.
You need to get a AFPR, or butcher yours and make it adjustable. I have a brand new JET adjustable one if you don't want to mess with yours, PM me about that if you want.
You will find best results running timing between +4 and +8 degrees advance, screw the factory settings for now.
You can splice in an in-line fuel pressure gauge in the INPUT line where is rubber, kind of in the front driver side corner of the engine bay. You'll see a pair of rubber fuel hoses making a 90* curve that are connected to hard routed fuel lines going under the car, and connected on the other end to the hard routed lines that go along your valve cover. The IN line is going to be slightly larger diameter and when looking at the throttle body, is the port closest to the driver side of the car. Using the 350 injectors you will want adjustability between 9-14 psi. 11 psi is a good starting point.
You'll get mixed opinions on the holley 670 on the TBI forum. It performs great for 350's but it's not a direct bolt-on, due to some technicality, do a search over there. edited: Oh yeah, one of the reasons is that you'll need to bore your manifold to 2" to match it.
Just as a side note, JET tech support is by far some of the best people I have ever dealt with, once I finally got through. Give them a call if you're still having problems.

 

Did you say you have the TBI from the 350 and replaced it with your 305 TB? If so you could remove the injectors from the 350 TB and send them out to be cleaned and use them. I second the idea of the caprice chip. Should be easy enough to find and WAY cheaper then a custom burn which you really don't need just yet with a bone stock engine. If the knock sensor isnt hooked up/working it could be causing be causing your problems, even if it isn't its still a really good idea to replace/fix it if its not working.

 

so I replaced the knock sensor, water pump, and advanced the timing to 4 1/2* btdc; all of which helped until my car wouldn't start back up, come to find out the alternator is dieing, as if that by itself wasn't bad enough the radiator sprung a leak, needless to say I was pissed. also it didn't help having someone in my class saying "I know what the problem is, its a pontiac" I was about ready to belt him one. anyway as soon as I get funds hopefully it will run again. I'm thinking of naming my car the "melinnium falcon" because its always breaking down or giving me some kind of problem. anyway sorry about the long post and thanks for letting me vent.
adam
ps I'm not in an auto mech program I'm learning to be a diesel mechanic

 

After you get the latest mess fixed up take a look at the spray pattern coming from the injectors, it should be a steady conical spray. Other then that you should be able to get it to run reasonably decent with the 305 chip for now by bumping up the fuel pressure a few lbs if you have an adjustable fuel pressure regulator, also you might wanna post this topic in the TBI forum and paste a link to this thread. I'm sure there are many other members with more knowledge on this particular swap then me as I have never done a 305 TBI to 350 TBi swap personally.

 

Lots of good hints an bad hints in this thread.

You need

350 knock sensor
350 ESC module
Leaving timing at 4* base to start
The truck PROMS and car PROMS ARE NOT COMPATABLE. If you cannot burn your own chips now than you need to look for a cop car chip from a LO5 TBI. You can get one here www.tbichips.com. Eventually you should look into burning your own. The stock prom should make the car idle but it will stall because of every parameter in the stock PROM needs to be altered to work with the larger injectors and displacment.

The TBI units on the truck and car are IDENTICAL except for the injectors. Swap the pods and make your regulator adjusable.

Autozone carries a TBI fuel pressure tester. You will tap into the feed line. You will need a minimun of 15 psi for that motor. The stock pump is very weak and cannot support much power at WOT. Read the stickys in the TBI forum for advice on the holley unit.

 

well I finally got my car fixed (again) as it turns out the radiator was fine, which was very odd. the alt on the other hand was junk, anyway now that it runs ok, (for now) I have a couple of more questions, one what kind of afpr should I be looking for and same questin for an esc module. I know its been a while since this post has been updated but I figured its already got most of the relevent info.