Hi all, i just got a 88 iroc-z 350 TPI with a 5-spd and i am very please with it so far.

One problem i am haveing is studdering when i rev up but i replace and O2 censor first day i got it. it will idle fine until i rev it up a little and then it will go down to around 500 rpms and will sometimes die.

Another problem i just discovered today is that it overheated very fast. i was driving it around for an hour and it was fine and then it sat for about hour or less and then i got 4 blocks and the check ingine light was on and the temp was in the red. then i let it cool down for 45 minutes drove it home and the temp stayed around 200 but the check ingine light was still on.

One last problem since this is a 5-spd 350 and spedo is way off and i was wondering if there is anyway to fix it cause if i don't i will most likey get a ticket very soon

 

Donno much about the tpi system so somebody else is gonna have to help ya on that. My guess is the TPS could be messed up but i remember reading that the TPS is almost always said to be what is wrong but almost never is. None the less could be that.

As for the overheating issue, sounds like its your fan, make sure it comes on when its supposed to, heck make sure it comes on at all. Change the thermostat its quick and cheap so might as well do it anyways.

Engine size has nothing to do with speedo readings it has to do with the gearing you have in that 10 bolt of yours and what size tire you're running. If you donno what kinda gears you have in the rear pull the cover, count the teeth on the ring and devide it by the teeth on the pinion. Then your gonna have to get a new speedo gear for your tranny to match. Would be kinda easier to just go the speed of traffic wouldnt you say

 

I dunno, but I think that engine size has a lot to do with speedo readings

The car prolly got a tranny swapped into it that has a different set of speedo gears, so do like he said and figure out what gears you have, then buy the right speedo gears for the trans.

- Justin

 

so true

 

are you sure its a 350?

the 5 speed never came behind a 350, so either the engine or the trans was swaped in

check the 8th digit of your vin, F is 302, 8 is 350, then look at the cast in size on the engine block, drivers side, behind the head on the bellhousing area, 5.0 is 305, 5.7 is 350

if it is a 350, but has the 305 injectors, it might effect driveablity, especially if the injectors are dirty, ect.

 

i figured he swapped it, i get tired of telling people no 350s came with any manual tranny but none the less it wouldnt matter if it was a 400

 

its is a 350 TPI 5-spd, 1st owner had dealer installed it, with 9 bolt rear end, has the z28 g92 package very rare car. it has 3.73 rear gears and i am thinking about 4.10s for it along with new headers. over heating probelm got fixed.

new problem kinda. i got the car from wisconsin which is about 1500 elevation ft, but i live in wyoming where it is about 6000ft and the car hasn't quite adjusted to it yet if at all. it is putting way to much gas in the engine and i was wondering if the computer should do that by it self, whcih i think it should, or do i have to adjust something. cause i am taking it to a mechanic here soon if not fixed

 

with the spedo problem again, all it has had is a tranny swap thats all so it just needs some gears or something change. if you take the speed it says on the spedo like 20, take it times 1.5 and u get 30 and that is my actual speed. so if it says 50 i am actually going 75, i had to use a gps to figure this all out haven't even tried to top it out yet, elevation problem is killing me

 

Disconnect the battery for 30 secs and itll clear the computer.

Also id bet money if you took the casting # off of that block it would come up as a 305. Gimme the # and i can find out for ya.

 

It sounds like an egr valve to me, its back by the distributer, it looks like a mushroom, you can take it off and clean it or buy a new one, they cost about $80 dollars new as for the speedo you need a new sending unit, or gear depending on the style, never done it with a manual before but on a 350 turbo they have different colored little gears that you can change to get an accurate reading, I would think this would also work for a 5 speed.

 

on a TPI you need to remove the upper plenum to access the EGR valve

 

ok, fixed the studdering problem, it needed a new mass air flow sensor and that fixed it right away. but i dont know what ill do about the spedo

 

well, speedo is strait forward, find out what rear gear you have, then get speedo gears to match

 

well, speedo is strait forward, find out what rear gear you have, then get speedo gears to match

Finding out what rear gears you have is simple based on speed and rpm. Getting the correct speedo gears may or may not be as straightforward.

The 9-bolt's choices of ratios are as follows: 2.77, 3.27, 3.45. There were aftermarket 3.70s at one point in time. The 10-bolt has similar ratios: 2.73, 3.23, 3.42, & 3.73. It's a matter of symantics I suppose but I feel there is a need to distinguish between the two styles because the gears are not interchangeable between the two. The 9-bolt uses a 7.75-inch diameter ring gear and the 10-bolt houses 7.625-inch gears.

The simplest way to determine current ratio is to pick a speed, like 45-mph. Keep the transmission in fourth (1:1 ratio) for a five-speed and "D" in an auto. For an auto, make sure the torque converter is locked. I give this info for others, not you because I know you have a five-speed. At 45-mph, what does your tach read? This value can be compared with ANY other third gen, as long as the other car's rear gear ratio is known. Then simple mathematics (ratios) is used to determine your ratio.

Report your findings here and I'll explain about how to select the proper speedo gears. Hopefully, the drive gear does not have to be changed. This is the one that can only be changed with the transmission apart!! Unfortunate but true. There were two available drive gears, a seven and nine tooth. You will need a seven tooth drive with a 21-tooth driven if you have 3.70s. Technically, this combo is correct for 3.73's but it's as close as you can get.