BigBoi4Lyph

So since ive bought my 89 iroc 5.7 auto tpi it had a surging while idling and you can also feel it have a surge when cruzing in the lower rpm range...

Im in autoshop at the high school so ive been able to chekc almost everything... including...

No codes what soever
New Iac
Check vehicle on a scope and all spark reading are perfect.
Cylanders are all running around the same. (check with an engine balance on a SCOPE)
Ajusted and chack TPS no dead spots and at .54
ajusted min air according to the tech article
New MAF
Good MAF Relays both power and burnoff
All injectors are comming on and click at the same rate.
Vaccume is good
Not a single vacume leek
Fuel pressur is at 40-48 psi Key on and idling
Check all connections

Its still suring as it was before and i cant figure it out.

Ive heard that the temp sending unit under the thermostate housing could be bad how can i check this?

Is their anything else i need to check before i assume my Computer is fried.

Thanks

SpitotRs305

the sending unit is just to give you a fancy gauge on the dash.. doesnt affect engine at all

BigBoi4Lyph

their are 2 sending units and 1 fan switch on my car and yours to i would assume

the one for the temp gauge is on the driver sidecylander head or block i cant remeber. and the 2nd sending unit is used by the computer and its the one under the thermostat hosing and ive read on here that when it goes bad it will thing the car is cold and dump fuel...

so thats why im wonder how i could check it but their are 2 sifferent sending units and 1 switch on out cars.

SpitotRs305

well it could be in either spot actually if the one on the intake has a 2 wire weather tight connector that is oval then it is just a gauge but it it is a circular than it is for the ecm..

bilms01

The 2 wire is the sensor with the weatherpac by the Tstat is the coolant temp sensor for the ECM.

The one in the driver side head has one wire should be a spade terminal is the temp sending unit, for the guage.

The fan switch is in the pass side head and has a round connector similar to the one on the knock sensor.

BigBoi4Lyph

yes, but will the ecm's sending unit going bad cause my car to surge?

bilms01

I suppose it could be possible I haven't seen it myself.

http://www.kemparts.com/TechTalk/tt13.asp this will give you an idea how to check the sensor.
Here is a couple enging control symptom charts out of a GM book I have Hope it helps.

cool84

do you have ac? if you open the hood with the engine running can you see/hear it surgeing? look at your ac compressor, it may be locking and unlocking the clutch and causeing it to surge as it drains power on and off.

BigBoi4Lyph

thanks Bilma yea i would have never thought but anything affecting the ECM's readings can do some crazy stuff.

I have Ac but its been baypassed since day one when i picked it up, thanks for the replay tho cool.

And Spitot Just to clear things up the single wire sending unit on the driver side of the block is for our temp gauge in the car. as our gauge is controled from the gound side haveing 2 wires woulnt be needed. I think it is one wire on most all cars for the temp gauge.

2 wire sending unit in our camaros are for the ECM only.

Any more info on what might be causing my surging is greatly apriciated its gettin very annoying driving it like this.

SpitotRs305

huh my haynes manual says the one wire plug is for the ecm and the 2 wire is for the gauge as the guage would need a power in but the ecm would not

HCR13

iTrader: (5)

It sounds like we're having the same problem. I replaced my spark plugs, tps and ecm. No help. Then I got a new distributor and everything got better, not fixed, but a whole lot better. Is it a quick constant surge, or delayed surges?

SpitotRs305

okay here is how to prove i am right... or wrong for that matter unplug that sensor on the intake and start the car if your temp gauge doesnt work i am right if it does then guess i am wrong...

when you swap engines to a carbed engine and dont have a use for the ecm temp sensor you still have to use the sensor on the manifold for you temp guage to work...

not to mention the temp guage is a stand alone with no connection to the ECM so it would need the power and a ground to be able to measure the resistance where as the ecm would only need the power as it has a common ground

BigBoi4Lyph

spitot yea the book is wrong or your misread it... the 2 wire connector works like this... the ecm is sending power through one of the wires on the connector to the unit. as the power goes through the sensor their is a resisance depending on tempature and then the new voltage is sent back to the ecm. thust requiring the 2 wires.

I did this the other day kinda semi checking my sensors... when i unplugged the single wire i lost my gauge and when i unplugged the 2 wire no cahnge at all

The gauge might run off both for an average reading but the 2 wire ismore for the ecm reading and the eingle wire runs directly to the gauge.

Hey HCR yea this problem is a head scratcher sofar. It dosent do it in open loop more then as soon as it his closeed loop mode it surges and it ranges from being very constant like surge surge surge and then surge...........surge............surge Like it takes a little break somtimes inbetween. You can really feel how mcuh is surges in DRive tho it just jumps and pulls when it does it...

Also to add to my list of checked items and replaced

Tune-up Cap rotor, wires, plugs

The old plugs were black suity... the car runs rich like the exaust burns your eyes kinda rich..

Also when i got the car the knock sensor was unplugged and i pluged it back in and no difference. but i do have a big exaust leek imbetween the pass side manifold and the y-pipe... I donno how much that would effect timming retard at idle..

I think i saw that the knock sensor isent even active at idle?

ANOTHER PEICE OF INFORMATION... when i go to start my car in the morning it had an alongated crank time like maybe 5-10 seconds before it starts.

And when i turn the car off it wont start i have to wait atleast 3 mins or so before the car will fire back up...

BigBoi4Lyph

Bump--anymore information would be very helpful thanks!

77monte

Did you try and check the coil's resistance to look for a weak coil? There should be information on testing all over

BigBoi4Lyph

i Never did that but my autoshop has a SCOPE that tests the ignitionssystem and everything was normal good spark all around so its not a spark issue.

DENN_SHAH

iTrader: (1)

the sending unit for the gage is the single wire in the left head, the ECM is the 2 wire, unplugged one wire has around 5 volts, the other is ground.
you can check the temp sending unit with the scanner & an infrared temp gun, they should read pretty close to the same.

hint, scopes can lie. using the scope you can unhook one of the wires & see what the kv is for that cylinder, it should max out the scope. another way to check coil output is to see how big of a gag the spark will actually jump across.
on the small cap systems with the external coil, you can pull the coil wire off the coil & have someone crank the motor over, it should fire down the side of the coil tower pretty much every time.

like you said, it may be running rich. the exhaust leak could be a problem, you may be getting a false reading from the O2 sensor because of it. check your AIR injection for proper operation.
check for leaking injectors or a leaking FPR. check the INT & BLM with the scanner. look at the O2 sensor & see if its working. also, if you have a 4 gas, check what the tail pipe readings are & see if they match up with what the O2 sensor says in the scanner.

Supervisor42

Five bucks says it's either the EGR valve not closing or the EGR solenoid valve. Do a manifold vacuum check at idle and post it. It should have a high reading as the rpm surges up and a low reading as it surges down. Post both of them.
(anybody notice I spelled solenoid correctly?)

BigBoi4Lyph

i wont be able to check anything else untill the 16th as im on sping break now and i dont have any gauges at my house yet...

Also i fixed the exaust leek yesterday and so their are no more leeks in the exaust. and it still surges.

Also im begining to remember when i had the scanner hooked up it had a temp reading on the scanner and it was like 60* and the car had been running for like 20 mins. (this was before i knew the temp sending unit could be mssed up)

Im not posituve but im remember seeing a really low temp reading.

But would that temp sending unit really cause my car to surge. I know it would cause it to run rich but surge?

But the EGR valve is fine is closed at idle like it should be.

But ill keep in mind all of this to check and ill put numbers up as soon as i have them.


DENN-- I actually hooked up a scanner to the car and the o2 is working great, BLM is 109 - 128 it changed and i dont remember what the int was what do all of these numbers mean?

D BERRY

iTrader: (2)

Yes, but spellings not cool on the net you know. Good info though!

Dave B

Supervisor42

If it was degrees C then 60C = 140F, which would be about right.

BigBoi4Lyph

yea i cant remember if it was C of F tho im going to check my temp sending unit with my DVOM cold and check it while its warming up and the output voltage should be around 4v cold and drop as the car warms up around .5v fully warmed up

rgarcia63

Any exhaust leak upstream of the O2 sensor should be repaired before attempting to diagnos other problems.

BigBoi4Lyph

Its been fixed for 2 days and its still surging. The leek was on the pass. side anyways so it woudlnt effect the o2 not much atleast

rgarcia63

I noticed your fuel pressure is 40-48psi key on and idling, that's what mine is with the key on and the engine off.

BigBoi4Lyph

my psi is 40-48 with the key on and engine off to and its the same at idle then when i loaded the engine it went up past 50

BigBoi4Lyph

Bump -- I did some more research im going to buy a vacuume gauge today and also some carb cleaner.Ive check all the vacuum around the engine iself but i havent checked both my vacuum canisters yes and the lines going to them.Also my heater works in all the positions so i dont have an Hvac leek.Cruse contol also works but i still am going to check the canister.I go a code last night driving on the freeway it was a 13 (i check when i got home) I beleave its oxigen sensor lean at cruze.Any more help with this info? Thanks

crapper_mekanic

I would say make sure you have good backpressure, and check to make sure your injector harness is hooked up proper. I have seen people mix up the #1 and #3 injector connections, and it was rich at idle, along with a surge in Drive, especially between 2000-2500 RPM. Almost felt like it wanted to shift into Overdrive, but couldn't. A lean flag on the wrong cylinder, and then sweentened up the wrong one, I think... P.S. You may want to consider getting an adjustable fuel regulator, and if you haven't, disconnect the coolant from the throttle body. COLD air burns better.

ultimatefighter

I had this same problem about a week ago. It was the front sensor on the intake manifold. It came undone. I plugged it back in and has been fine ever since.

BigBoi4Lyph

The info is great guys, i did some more checking. the surging is not associated with any sensors what so ever all sensors have great and in range readings.

So i check all of my injectors out

I had 5 injectors with a resistance of .007

1 with .003

1 with .015

and one with .017

I think those readings are bad lol

What # injectors and brand should i buy that i wont have to mess with my computer.

im also going to buy an ajustable fuel pressure regulator

I did a fuel pressure test and results are:

45psi key on engine off

41psi at idle

and the fuel pressure stays stady even when the car is surging.

I also did a vaccum test.

I got 17hg when car surges up and 13hg was my lowest reading when the car surges down

I also checked my injector connections yesterday i switched all of them around and they all seemed to be hooked up to the correct injectors.

Thanks alot guys.

Also i pulled out the egr solenoid and its broken and in the back of it it had a 3rd connection that didnt have anything plugged into it it looked like a vacuum line went to it but the vacuum diagram sayd nothing goes too it but the 2 lines on top.

Thanks again

DENN_SHAH

iTrader: (1)

i take it those readings from the injectors are 3, 7, 15, & 17 ohms.
i forget off hand, but i think the injectors should be between 12 ~ 16 ohms.
they may be your problem, or they may not be, but you need a set of injectors anyway because the low resistance of most of them could damage your ECM.
some people only replace the ones that are bad, which is fine if you only have 1 or 2 bad & the rest are in good condition. but with 6 bad, there is no reason not to replace them all with a set of new of injectors.
alot of people here like the ford svo injectors & have had good luck with them.
i believe you would need the #22 (pink top) ford injectors if your motor is stock & you can't burn your own chips. if you can burn your own chips, then a set of #24 (blue top) fords should be fine & let you have some room for some mods later on.
if you use the ford injectors, be sure get the GM injector O-ring kit.


egr solenoid only has 2 lines going to it, 1 is from the intake, the other goes to the valve. the third port on it is the vent port & when new it has a foam filter on it.

BigBoi4Lyph

Hey thanks fr the reply.And the injector readings i posted are when they each read. i got .003 .007 .015 .017 on my dvom and its working perfectly i verified by checking many other sensors and such on my car and their readings all turned out perfect.I heard for the ford injectors you have to grind down the fuel rail because they are shorter injectors.also i havent seen a #22 injector from ford yet only 21 and 24Accel makes a #23 for our cars that would be a nice upgrade and i doubt it would effect your pcm enough to have to burn a chip 269.00 for all 8 off summit.This surging is just killing me and the car is dieing even easyer now(stalling out) even in park or nutral Im going to go crazy...But any suggestion on injectors is welcome i dont want to spend a whole lot for then 300 and im also going to pick up a fuel pressure reg. ajustable.And i dont want to have to burn a prom...Thanks

BigBoi4Lyph

Today i checked the injectors again and i guess my dvom was set wrong here are my actual readings. they are almost all fried one is shorted...

Im going to pick up some ford pink tops #22's on the 9th of may

17
15
14
9
9
8
7
0 - cylander 8 has the shorted injector... lol

they are thoswe damn Multec injectors

anyways im pretty shure this explains my surging idle, slight random miss, and backfireing.

So i will get back on here and post my resulats after the 9th sometime when i get the injectors