JCee

88 350 Iroc
Several cranks to start only when cold and/or sits 3-4 hrs +
Narrowing it to this for now so questions are how to see if working; maybe someting quick and simple like pulling out and powering up. Currently I'm getting no codes. SES is working.
1.What ohm reading should I read across inj.- I measured 4
2.How would I check volt to CSI and what should I read; each pin to ground, across pins ?
3.Read there was another temp switch/timer that sends signal to it - where is it or what is it part of and could it go bad.
4. To remove do I have to pull fuel rail or just pop the sucker out ?
5. Can the CSI cause up and down idle at cold ?
6. COuld temp sensor cause it - but you'd think it would show up in SES readings

Any help would be greatly appreciated
Thx JCee

Morley

Check pin to pin while cranking the car, should be 12 volts or there abouts.
It is a Thermo-time switch located at the front of the intake manifold (the larger of the 2 there)
To remove the CSI you need to remove one of the lower runner bolts, it goes through a tab on the CSI.
No and no

The lack of a functioning CSI could cause an un-stable idle while warming up (first few seconds of running) due to a lack of fuel during start.

377Z

iTrader: (1)

The injector has an internal short--should be around 16 ohms. I think you already found your problem.

Viprklr

iTrader: (5)

Are you sure about that? Mine, which worked when I removed it, had a resistance of ~ 4 ohms.

377Z

iTrader: (1)

I am pretty sure; I don't think any of our cars came with low impedance injectors. To verify, check the rest of your injectors--they should all be within an ohm or so of each other, and all 9 should be the same--If you find the rest are around 16 ohms, then just change that one injector. If you find that any other of the injectors are low (i.e. 6 are around 16 ohms, the others are significantly lower), change them all. I had a few go bad on my '91 Z28, and only changed the bad ones. Then I had a few more go. The second time I changed the rest of the old ones as I had heard that once they start going, the ones that are still good are not far behind. Nothing like doing the same job twice because you weren't aware of something. Plus, since I got the first couple from the dealer, I wanted to make sure they all matched (& were the same company) so I was stuck with getting the rest from them. (I was ignorant to the fact that you could get a set of SVO injectors for ~$220 I paid ALOT more than that from the stealer, err, I mean dealer)

Though its waaay out of spec at 4 ohms, it may well still work as it is not completely shorted, since you read 4 ohms maybe its shorted part way though the windings so it still opens when voltage is applied but its certainly not working properly.

I'm pretty sure all TPI cars used the high impedance injectors regardless of whether they had 8 or 9, maybe someone can verify because I never had one with 9.

Good luck, hope this helps.

Morley

Don't go by the main injectors. The CSI is an independent system, it has no ties to the other 8 injectors or the ECM in any way, shape or form. It could very very well be low impedance.

377Z

iTrader: (1)

Though its an independent system, I doubt there is a special separate driver for one low impedance injector for a cold start system. The primary benefit of low impedance injectors are shorter trigger time for a given flowed volume of fuel versus a high impedance injector, and the slight enrichment that is required for a cold start.

Sure fire check: Either look into a service manual and obtain the proper resistance, or find someone with a properly functioning CSI car and measure it.

JCee

Morley
Thanks for info -
let me ask you this --
the CSI connector is the same as cylinder inj connectors ?
This one was badly corroaded along with inj conector (still read the 4 to 4.4 ohms when cleaned)
Additionally found that the thermo switch had a bent pin.
Later JCee

Morley

Yes, they are the same and can be had at most parts stores that carry electrical connrctors.

JCee

For what it is worth
Installed new CSI thrmo switch/sensor - about $30 from Oreillys.
New connector (approx $11 from NAPA) for thrmo swtch as old one was messed up and the old switch showed evidence of bad bent pin, folded @ 45 degrees plus.
While I was there changed out CTS.
as mentioned before the CSI connector and the pins on the CSI were corroded so I cleaned them - (the new connector was really for the purpose of changing on CSI but it fits the switch also) -
Fired right up after sitting for a week while I was helping the USMC.
Will see if continues to show a positive attitude.
Conclusion
Not a root cause job of evaluating.
Since I didn't check to see if 12v "across" the CSI connector my assumption, I hate that word, is that there wasn't a good or any connection at the thermo switch - mostly due to the evidence of the bent pin and very poor condition of the connector. The corrosion was your normal green stuff but nothing likely to affect 12v - don't know the current on the thing -
The CSI continues to work even though it shows 4 to 4.4 ohms.
Not to say that is the spec or there isn't a problem with it.

Next to the pulsing idle

JCee